This article is a brief introduction to hadith and its sciences for a Muslim beginner. It will discuss the following topics:
- 1. Why is the Sunnah Necessary?
- 2. What is a Hadith?
- 3. Classification of Hadith
- 4. Stages of Hadith
- 5. Hadith Collections
- 6. Sahih Bukhari and Sahih Muslim
- 7. Manners of Learning Hadith
- 8. Difficult Ahadith
1. Why is the Sunnah Necessary?
There are six things to understand:
- Allah commands us to obey the Prophet (SAW) in the Quran
- The Prophet (SAW) did receive revelation outside the Quran
- The sayings of the Prophet (SAW) are needed
- The hadith sciences being ‘manmade’ does not make it especially unreliable
- Most hadith being non-definitive does not mean we are not required to follow them
- There are wisdoms for Allah not putting everything in the Quran.
1.1 Allah Commands Obedience to the Prophet
First of all, Allah says in the Quran ⟪Obey Allah and obey the Messenger⟫ at least five times in the Quran (4:59, 5:92, 24:54, 47:33, 64:12).
Note how Allah repeats the word “obey” for the Messenger. It is not one comman, but two separate commands: 1) obey Allah (through the Quran) and 2) obey the Messenger (through his Sunnah). This goes against anyone who claims obeying the Messenger is only by following the Quran.
Secondly, Allah says ⟪Say, [O Muhammad], “If you should love Allah, then follow me, [so] Allah will love you and forgive you your sins.”⟫ (3:31)
Allah links His love to following the Messenger (SAW).
Thirdly, Allah says ⟪O you who have believed, obey Allah and obey the Messenger and the leaders among you. And if you disagree over anything, refer it to Allah and the Messenger, if you should believe in Allah and the Last Day. That is the best [way] and best in result.⟫ (4:59)
In this verse, Allah explicitly says the final judges are always Allah and His Messenger. He does not say the final judge is Allah alone, so no one can claim that final judge is always just the Quran because it is Allah’s speech.
Fourthly, Allah says ⟪But no, by your Lord, they will not [truly] believe until they make you, [O Muhammad], judge concerning that over which they dispute among themselves and then find within themselves no discomfort from what you have judged and submit in [full, willing] submission.⟫ (4:65)
In this verse, Allah obligates everyone to take the Prophet (SAW) as the judge in all disputes. Today, we can only do so by referring back to his actions and sayings.
Fifthly, Allah says ⟪There has certainly been for you in the Messenger of Allah an excellent pattern⟫ (33:21)
In this verse, Allah praises the pattern of the Prophet (SAW), calling it “excellent” (hasanah) and invites us to follow it.
There are many more verses on this topic. 
1.2 Prophet Received Other Revelation
Some people today dispute the fact that the Prophet (SAW) received revelation in addition to the Quran, saying the Quran is the only revelation the Prophet (SAW) ever got. This is plainly false even according to the Quran.
Firstly, Allah says ⟪Your companion [Muhammad] has not strayed, nor has he erred, Nor does he speak from [his own] inclination. It is not but a revelation revealed,⟫ (53:2-4)
These verses indicate that the Prophet (SAW) did not speak simply from his desires in any part of his life. If he ever made a mistake, Allah would quickly correct him. So, if he says something and there is no correction, it is necessary to follow him.
Secondly, there are many instances in the Quran of Allah referencing revelation the Prophet received not in the Quran.
For example, Allah says ⟪And [remember] when the Prophet confided to one of his wives a statement; and when she informed [another] of it and Allah showed it to him, he made known part of it and ignored a part. And when he informed her about it, she said, “Who told you this?” He said, “I was informed by the Knowing, the Acquainted.”⟫ (66:3)
Here, Allah says the Prophet (SAW) was informed by revelation about something one of his wives said secretly to another. Obviously, nothing of this sort exists in the Quran itself. Rather, he was informed outside the Quran.
Another example is when Allah says about the old direction of prayer to Jerusalem ⟪And We did not make the qiblah which you used to face except that We might make evident who would follow the Messenger from who would turn back on his heels.⟫ (2:143)
Here, Allah says He legislated the qiblah to Jerusalem, but no such verse exists in the Quran. So, it was something given to the Prophet (SAW) outside the Quran.
Another example is when Allah says ⟪And if you fear [an enemy, then pray] on foot or riding. But when you are secure, then remember Allah [in prayer], as He has taught you that which you did not [previously] know.⟫ (2:239)
Here, Allah says the way of prayer was ⟪taught⟫ by Allah. However, no verses in the Quran clearly teach the method of prayer. At most, some verses reference parts of prayer without ever teaching how to pray. So, this refers to the teachings given to the Prophet (SAW) outside the Quran.
1.3 Importance of the Sayings of the Prophet (SAW)
Some people claim we only need the practices of the Prophet (SAW) and they were transmitted by the practice of the Muslims generation to generation, like how to pray. They claim we do not need individual or solitary narrations from the Prophet (SAW).
This claim is wrong because Allah never qualifies what type of transmission we are required to obey. Allah says ⟪Obey Allah and obey the Messenger⟫ without saying “only when it is proven through generational practice.”
So, as long as the transmission is authentic and it is likely to be true, we are required to follow it. It is not possible to limit it to practices passed on generation to generation, but it is possible to say those practices are more strongly proven.
One question that arises when only relying on Muslim practice is what to do when their practice does not agree, like what dua to make before reciting Fatihah or whether to raise hands when doing ruku. Which practice will one follow?
The only way to know which one is correct is by investigating the hadith evidence of different views.
1.4 Are Ahadith Manmade?
Some people criticize the sciences of hadith as being manmade.
However, even the sciences of the Quran are manmade. After all, the Quran was written by men, compiled by men, carried to the different lands by men, and memorized generation to generation by men.
Allah says in the Quran ⟪Indeed, it is We who sent down the Reminder and indeed, We will be its guardian.⟫ (15:9)
Although some people said ⟪Reminder⟫ here means Quran, the word itself is broad enough to include hadith. Allah protected both the reminder in the Quran and the Sunnah. He protected the Sunnah by creating scholars who memorized the ahadith, created a science to classify them, authenticated the authentic and weakened the weak, and collected them into the many collections we have today.
So, both the Quran and Sunnah were preserved by the hands of men with Allah’s power guiding the process.
The only difference is that the Quran is mostly definitive while the ahadith are usually non-definitive, but both must be followed.
1.5 Definitive and Non-Definitive
Knowledge is either definitive or non-definitive. Definitive knowledge is that knowledge which is known to be true with zero doubt. Non-definitive knowledge is that knowledge which is known to be true but with the possibility of some doubt. It can still be strongly proven, but it has some room for doubt.
The Quran’s transmission is definitive and mutawatir. There are so many memorizers and transmitters in every generation that there remains no room for doubt that the Quran actually comes from the mouth of the Prophet (SAW).
Some ahadith are transmitted definitively, like mutawatir ahadith as will be mentioned later. However, most of the authentic hadith literature is non-definitive knowledge.
Someone might claim we do not need to follow non-definitive knowledge. However, this claim goes against the Quran, Sunnah, and rationality.
As for the Quran, Allah repeatedly mentions how the Christians and the Jews were given scriptures that they were required to follow, but their scriptures were not transmitted definitively as should be obvious from the fact of their corruption. So, they were required to follow scripture even though it was non-definitive.
Why would it be different for Muslims when God has commanded them to obey Allah and the Prophet (SAW)? They are required to obey even if some of the commands are transmitted to them non-definitively.
As for the Sunnah, the Prophet (SAW) is reported to have sent letters to the kings of the different lands asking them to accept Islam and follow him. He also sent messengers to lands like Yemen to teach them Islam. Being told something through one or two messengers is non-definitive knowledge. If it was not binding to follow this knowledge, there would be no point in the Prophet sending those messengers to teach Islam.
As for rationality, humans follow non-definitive knowledge all the time in their daily life. Almost everything a person relies on everyday like the bus schedule is non-definitive. Why would he stop using his rationality in this case when it is most important?
1.6 Wisdoms of Having the Sunnah
Firstly, having the details of everything in the Quran would lengthen it and make it almost like a legal textbook. However, the Quran was sent down as a concise book of guidance that points a person in the correct direction, like the Sunnah. It was not sent down to list every law one needs to know. Doing that would make it not concise.
Some people claim the Quran contains everything because Allah says ⟪And We have sent down to you the Book as clarification for all things and as guidance and mercy and good tidings for the Muslims.⟫ (16:89)
But, that is a misinterpretation of this verse, and ⟪clarification for all things⟫ means the Quran clarifies everything you need to know by mentioning some things explicitly and pointing to some things indirectly by mentioning where one needs to go for more details. So, when a person receives a command from the Prophet (SAW) and the Quran commands him to obey the Prophet (SAW), that is clarification from the Quran.
The interpretation that ⟪clarification for all things⟫ means the Quran explicitly mentions everything in the religion is proven wrong simply by the fact that the Quran does not teach the exact method of prayer.
Secondly, Allah loved the Prophet (SAW) and wished to give him a high status to the point that He said ⟪And raised high for you your mention.⟫ (94:4)
Obligating people to follow his sayings and actions is one way Allah raised the Prophet (SAW)’s mention and status.
Thirdly, creating the subject of the Sunnah and hadith gives people the opportunity to gain rewards by working hard for the sake of Allah and the Prophet (SAW), by collecting, classifying, learning, and analyzing ahadith. It is a chance to gain good deeds with Allah.
Fourthly, many actions, like prayer, are easier to show than tell. That is why the Prophet (SAW) taught prayer by showing how it is performed instead of Allah explaining exactly how to do it in words.
2. What is a Hadith?
A hadith (pl. ahadith) or khabr refers to one narration about a saying, action, or approval of (usually) the Prophet (SAW).
Sometimes “hadith” can refer to the concept of narrations, not an individual hadith or all ahadith. 
A single hadith is made up of two parts: 1) the sanad (chain), and 2) the matn (content).
Today, a person will mostly get a hadith from a hadith collection, which is a collection of ahadith by a scholar.
An example of a full hadith taken from the collection Sahih Bukhari:
Musaddad narrated to us, saying: Yahya narrated to us from Shubah from Qatadah from Anas from the Prophet (SAW) […]: “None of you believes until he loves for his brother what he loves for himself.”Sahih Bukhari 13
2.1 Sanad (Chain)
The early hadith scholars were concerned about verifying the narrations of the Prophet (SAW), so they were not satisfied if Qatadah (who is a generation after the Prophet) said, “The Prophet said XYZ.”
They would ask, “Who told you that?”
So, Qatadah would instead say, “According to Anas (a companion of the Prophet), the Prophet said XYZ”
This became common practice. Then, Qatadah’s student Shubah would say, “According to Qatadah: According to Anas, the Prophet said XYZ.”
Then, in the next generation more names were added.
This creates a chain of narrators for the hadith back to the Prophet (SAW).
In the hadith quoted above, the chain of narrators is, “Musaddad narrated to us, saying: Yahya narrated to us from Shubah from Qatadah from Anas.”
The speaker in “Musaddad narrated to us” is the collector of the collection the hadith is taken from, Bukhari.
So, the chain is the following: Bukhari ← Musaddad ← Yahya ← Shubah ← Qatadah ← Anas ← Prophet (SAW). In this particular chain, there are five people between Bukhari and the Prophet (SAW).
The significance of the chain is that it is used when determining the authenticity of a narration, as will be elaborated later.
2.2 Matn (Content)
The matn of a hadith refers to the actual content it conveys, which is either a saying, action, or approval of the Prophet (SAW).
In the above example, the matn is, “None of you believers until he loves for his brother what he loves for himself.”
2.3 Related Subjects
Usul al-Hadith is the subject of studying what ahadith are and how to classify them. The following section on hadith classification will heavily draw from Usul al-Hadith.
Ilm ur-Rijaal is the subject of narrator biographies and gradings. Books of ilm ur-rijal often contain brief explanations about when a narrator lived, which teachers he narrated from, which students narrated from him, and what the hadith scholars thought about their reliability.
Ilal (عِلَل) is a genre of books that study the subtle problems in some ahadith.
Sunan and Musnad are common names for hadith collections. Musannaf is also an important collection name, but they often contain the statements of companions and tabi’een.
Shuruh al-Hadith is the genre of books that explain the meanings of the ahadith in a hadith collection. Sharh means “explanation” or “elaboration.”
3. Classification of Hadith
This section is basically a brief overview of Usul al-Hadith.
3.1 Mutawatir and Ahaad
The scholars of hadith divided narrations into two:
- Mutawatir: There are so many different routes of transmission and so many different narrators who narrate it in every generation that it is impossible for them to have made the same mistake or lied the same lie. 
- Ahaad: Any hadith that is not mutawatir. It has some chains of transmission, but not enough to reach the level of mutawatir.
Mutawatir ahadith are definitive and true without doubt. An example is the Prophet (SAW) saying, “Whoever lies about me, let him take his seat in the fire.”
Another example is the attribution of many hadith collections to their authors, like Sahih Bukhari to Imam Bukhari. It is mutawatir because many students narrated and wrote from him and many students narrated from them and so on until today.
The sciences of hadith are less concerned with mutawatir than they are with ahaad because mutawatir does not need classification.
Ahaad hadith need classification from authentic to inauthentic. However, acting on authentic ahaad hadith is still necessary because it is knowledge even if non-definitive.
The Prophet (SAW) sending messengers to different kings would be ahaad narrations to those kings, but he still expected them to follow the messages.
Likewise, we are expected to follow ahaad narrations, as long as they are determined to be authentic.
3.2 End of the Chain
The scholars of hadith divided a hadith according to the end of its chain into three:
- Marfū’: The doer or speaker at the end of the chain is the Prophet (SAW).
- Mawqūf: The doer or speaker at the end of the chain is a companion, and he does not attribute it to the Prophet (SAW) explicitly.
- Maqtū’: The doer or speaker at the end of the chain is someone lower than a companion.
When we say the word “hadith,” we usually mean marfū’ hadith.
As for the opinions or statements of the companions, there is more detail to how and when they are used, but that is a topic for Usul al-Fiqh.
3.3 Connectedness of the Chain
The scholars then divided a hadith according to the connectedness of its chain into two:
- Mawsūl: The chain is connected with no breaks in it.
- Munqati’: The chain is broken, with some people missing in the middle.
A special category of munqati’ is mursal: When a tabi’i narrates from the Prophet (SAW) directly without mentioning his source.
Mursal ahadith have difference of opinion about their authenticity, because it is possible the tabi’i is narrating from a companion and that would be authentic or he is narrating from another tabi’i who is weak and that would be inauthentic.
Some tabi’i scholars were known for being careful whom they narrated from and some were not. Additionally, the senior generation of the tabi’i scholars is more likely to narrate from a companion than from someone else. The younger generation is more likely to narrate from another tabi’i.
The scholars divided a hadith in terms of its authenticity into three: sahih (authentic), hasan (fair), and da’eef (weak).
A sahih hadith is a hadith that fulfills five conditions:
- The chain is connected
- Every narrator in the chain has ‘adalah (moral uprightness and honesty)
- Every narrator in the chain has dabt (reliability and accuracy in transmission)
- The hadith has no shuzuz or nakarah . It does not contradict the narration of someone more authentic.
- The hadith has no ilal (singular: illah) i.e. subtle defects. 
Sahih can have multiple levels. For example, narrations by an narrator with extremely high dabt would be higher in level than those of someone just a bit below him in dabt.
A hasan hadith has various definitions, but the best definition is that it simply does not reach the level of sahih for some reason (usually one of the narrators is not high in dabt) but is also not completely weak.
Hasan sahih was a term used by Tirmidhi in his collection, and the most correct explanation is that it is synonymous with sahih. Some people proposed the idea that hasan sahih means there were two chains, one hasan and one sahih, or that it was in the middle of hasan and sahih. But, this is not correct.
Sahih li-ghairihi (meaning: sahih but not in itself) is when there are multiple hasan chains for a narration that add up to making the narration sahih.
A da’eef hadith is a hadith that is below the level of hasan. Usually, this means that there is some disconnect in the chain, one of the narrators has heavy problems in dabt, one of the narrators has problems in adalah, or it contradicts stronger narrations.
Hasan li-ghairihi (meaning: hasan but not in itself) is when there are multiple da’eef chains for a narration that add up to making it hasan.
An extremely da’eef (or matrūh) hadith is when a hadith is even lower than normal da’eef.
A mawdhū’ hadith is a hadith that is considered fabricated. Some said this is when it contains a known liar and contradicts more authentic information or when a narrator admits to fabricating a hadith.
Being ghareeb refers to being unique or solitary in some sense. It is possible to be completely ghareeb or relatively ghareeb.
An example of completely ghareeb is if someone is the only one to narrate a hadith from the Prophet (SAW).
An example of relatively ghareeb is if someone is the only one to narrate a particular hadith from a teacher even though that hadith might exist from other people.
Ghareeb ahadith are not automatically weak. As long as the narrators are strong and there is no reason to doubt the narration, it can be considered sahih.
But, sometimes, there can be reason to doubt the narration. For example, if only one (relatively weaker) student narrates a hadith from a teacher but more prolific and strong students from the same teacher do not mention it, that is a reason to doubt the narration.
The hadith “Actions are according to intention” is ghareeb until the fourth narrator.
Yahya ibn Sa’eed al-Ansari ← Muhammad ibn Ibrahim ← Alqamah ibn Waqqās ← Umar ibn al-Khattab ← Messenger of Allah (SAW).
Umar (RA) was the only companion to narrate this from the Prophet. Alqamah was the only one to narrate it from Umar. Muhammad was the only one to narrate it from Alqamah. Yahya was the only one to narrate it from Muhammad.
But, they are all strong narrators and there is no reason to doubt their narration. So, it is a sahih hadith.
After Yahya, many of his students narrated the hadith from him.
3.6 ‘An‘anah and Tadlees
‘An‘anah (عنعنة) is when someone narrates from someone else without explicitly saying he heard from him or that the person narrated to him.
The most common example is if someone just says عن (from) which is why it is called ‘an‘anah. Another example is if someone just says “X said” without saying “I heard X say” or “X narrated to me.”
If someone does ‘an‘anah, there are two possibilities:
- It is from someone they obviously did not hear from
- This is fine because it causes no confusion. For example, I can say “The Prophet said” and no one would imagine I am claiming I heard from the Prophet.
- It is from someone contemporary to them whom they could have met. In this case, there are two further possibilities:
- They actually did hear the hadith from them
- That is fine.
- They did not hear the hadith from them directly, maybe hearing it from a person in between
- That is problematic because him saying “X said” or “from X” leads to the misconception that he actually heard from this person. So, the ambiguity is almost deceptive.
- They actually did hear the hadith from them
Someone who is known for doing ‘an‘anah without having heard directly is called a mudallis.
A mudallis is usually not trusted in his ‘an‘anah narrations except if he explicitly says he heard a certain hadith. However, ‘an‘anah is not inherently problematic as long as a trustworthy non-mudallis narrator is doing it.
Tadlees is not the same as lying because the mudallis does not actually lie. He simply drops a narrator in between and uses ambiguous words. If someone says “I heard X say” when he never heard X say it, that is a lie. A mudallis who says “X said” without hearing X say it is not lying.
3.7 Riwayah bil-Ma’na
Riwayah bil-Ma’na refers to when someone narrates a hadith according to meaning rather than exact wording. This can be by changing the sentence structure slightly, using synonyms, summarizing, or changing the order of things.
The vast majority of hadith scholars allow it if the doer is knowledgeable enough to know what the Prophet (SAW) actually meant, but it is not preferred. It is always preferred to narrate exactly or almost exactly as was transmitted, and this is what the most accurate scholars of hadith did.
Narration by meaning can be done 1) intentionally or 2) unintentionally.
- Intentional would include when someone forgets the exact wording of a hadith but remembers the meaning so intentionally narrates the meaning, or if he forgets a specific word , or he wishes to summarize the hadith.
- Unintentional would be when someone misremembers the exact wording or a specific word but remembers the meaning and so unintentionally narrates a synonymous wording.
Often, multiple versions of the same hadith exist because some of the narrators narrated by meaning.
When there are multiple wordings, the strongest wording is usually the one narrated by the most accurate narrators or by the majority of narrators. However, determining this is not always an exact science.
3.8 Differences in Grading
Although there are many common principles of classifying ahadith, there is also much room for difference in the general rules and the specific application. 
Because of this, it is not uncommon to find scholars differing about the exact authenticity of a particular hadith. There are some ahadith that the vast majority agree are sahih, there are some the vast majority agree are weak, then there are some where there is no vast majority for either side.
Do not assume, then, that the grading you see on a site like sunnah.com is the only possible grading.
4. Stages of Hadith
The subject of hadith has gone through various stages since the time of the Prophet (SAW).
4.1 Stage 1: Lifetime of the Prophet
In the lifetime of the Prophet (SAW), the companions used to narrate the statements of the Prophet to each other. Initially, he told them not to write anything from him because he did not want the Quran to be confused.
The Prophet (SAW) said, “Do not write from me. Whoever wrote from me other than the Quran should erase it. But, narrate from me, there is no harm in that. And whoever lies about me (deliberately), let him take his seat in the fire.” (Sahih Muslim)
The companions understood that the Prophet (SAW) was given revelation in addition to the Quran, so they treated his statements like revelation.
Later on, when the risk of confusion with the Quran was gone, the Prophet (SAW) lifted this ban on writing, and many companions started writing his ahadith.
Among the companions that wrote from the Prophet (SAW) include Abdullah ibn Amr ibn al-Aas , Jabir ibn Abdullah, Sa’d ibn Ubadah, etc.
Other companions like Abu Hurairah (RA) mostly spent their time memorizing rather than writing but wrote after the Prophet (SAW)’s death. 
Most of the writings of the companions were subsumed into later works and combined with them. The closest we have of a fully independent work from a companion today is the Sahifah of Hammam who wrote his book from his teacher Abu Hurairah in his lifetime. 
4.2 Stage 2: Khulafa Rashidun
In the time of the first four Caliphs, the state of hadith was not much different from the state of hadith in the life of the Prophet (SAW).
There was much concern about the Quran, since the Quran was compiled in the reign of Abu Bakr then in the reign of Uthman (RA), so many of the senior companions were still concerned about confusion of hadith with the Quran.
Al-Khatib al-Baghdadi says: “Those who disliked writing (hadith) in the first generation only disliked it because they did not want anything to overshadow the Book of Allah or that people become more involved in the Quran over hadith.”
The companions saw how the previous nations did not pay much attention to their books and more to their extra writings, and they did not want that to happen to the Quran.
Their concern is what led the Quran today to be an extremely mass-transmitted text with thousands of memorizers in every generation.
However, they still narrated and learned from hadith and did not dispute the fact that the Prophet’s teachings hold weight. In this stage, many of the companions narrated hadith to their students. If a problem arose which needed an answer from the Prophet (SAW), they would narrate from him to respond to the problem.
In this stage, the students of companions were usually people close to them, like their family, servants, and friends. For example, from Ibn Umar narrates his servant Nafi and from Aisha (RA) narrates her nephew Urwah ibn Zubair.
4.3 Stage 3: Second Generation
The earlier tabi’i scholars were also hesitant to write.  But, by the time of the intermediate and later tabi’i scholars, writing became common to help remember the ahadith.
The students and gatherings of ahadith began to grow larger in this time period, so one tabi’i would have many students but usually from the same area.
Saeed ibn Musayyab and Zuhri are major hadith scholars of the second generation.
4.4 Stage 4: Third and Fourth Generations
In the third and fourth generations, the gatherings of hadith grew larger such that one scholar would have many students from different lands. People started travelling to different places to get hadith.
Imam Malik wrote his Muwatta, collecting narrations from many of the scholars of Madinah, and other collections were written in this time like the Musannaf of Abdur-Razzaq.
Sufyan ibn Uyaynah, Shubah, and Yahya ibn Saeed are other major hadith scholars in this generation.
4.5 Stage 5: Era of Hadith Criticism and Musnads
After that came scholars like Ibn al-Mubarak, Ibn al-Madini, Ibn Ma’een, Ahmad ibn Hanbal, and Ishaq ibn Rahawaih, who narrated hadith and were experts in the biographies of narrators.
Often, when you wish to figure out the reliability of a narrator, you would listen to the criticism or praise of some of these scholars.
Imam Ahmad wrote his Musnad, and many other Musnads were written at this time collecting ahadith from different lands into single collections. Musnad is a collection that organizes ahadith according to narrators.
4.6 Stage 6: Era of Sunans
Afterwards came scholars like Bukhari, Abu Hatim, Abu Dawud, Muslim, then Nasai and Ibn Khuzaimah. They learned from many different hadith narrators and wrote down collections of hadith.
There were many collections written in this time, intending not just to collect but to have some level of reliability for the hadith collected and to divide the ahadith by topic. Sunan refers to a collection that organizes ahadith according to topic.
Scholars like Bukhari, Muslim, and Ibn Khuzaimah wrote Sahih collections, meaning collections that only intended to include authentic narrations.
5. Hadith Collections
5.1 Collections with Chains
The following are some of the major collections of ahadith that were written with the author’s chain to the Prophet (SAW) for every hadith.
The Muwatta of Imam Malik (d. 179) is one of the major collections from the third generation. It records authentic narrations from the Prophet (SAW), but also records opinions of the companions and tabi’īn. It also contains brief commentary about fiqh from Imam Malik.
The Musannaf of Abdur-Razzaq (d. 211) is one of the earliest collections that we have containing many opinions from the companions and tabi’īn and also some ahadith. The Musannaf of Ibn Abi Shaibah (d. 235) is similar.
The Musnad of Imam Ahmad (d. 241) is a large collection of ahadith of the Prophet (SAW) containing almost 30,000 ahadith. A lot of those are repetitions and different narrations of the same thing.
The collection is organized by narrator, not by topic. Imam Ahmad did not condition complete authenticity in his collection, but he intended to compile every narration that was known to the hadith scholars. So, if a hadith is not found in the Musnad, that does not bode well for the reliability of the hadith.
The Sunan of Darimi (d. 255) is a collection of about 3546 ahadith organized by topic.
The Sahih of Imam Bukhari (d. 256) is a collection of 7500 ahadith without excluding repetitions in which Imam Bukhari intended to only include sahih ahadith.
This book, Imam Bukhari being one of the greatest hadith scholars of his generation, became the most relied upon book after the Quran. The scholars of the ummah considered Bukhari’s collection to be like no one else’s.
The Sahih is organized by topic as are the rest of the collections.
Imam Bukhari also wrote Al-Adab al-Mufrad, a collection on the qualities and manners of the Prophet (SAW).
The Sahih of Imam Muslim (d. 261) is another collection written to solely consist of sahih ahadith. It has about 7500 ahadith.
Imam Muslim was also one of the greatest scholars of the generation, and his book is the most authentic overall after Sahih Bukhari and the Quran.
The Sahihayn is a term to refer to the two Sahihs of Bukhari and Muslim respectively.
The Sunan of Abu Dawud (d. 275) is a short collection of about 5,200 ahadith. Abu Dawud wrote a letter explaining the methodology of his book. He included in his collection ahadith that were not extremely weak, and he pointed out extreme weakness if there was any. But, that does not mean every hadith he included is sahih. It is possible for there to be a weak but not extremely weak hadith he includes without commenting on it.
The Sunan of Ibn Majah (d. 273) is a collection of about 4,300 ahadith. His collection is the weakest of the Sunan as-Sittah.
The Sunan of Tirmidhi (d. 279) is a collection of about 4,400 ahadith. Tirmidhi often noted his grading of the hadith after narrating it, and he sometimes commented about the fiqh rulings related to a hadith. Tirmidhi was a student of Imam Bukhari.
Tirmidhi also wrote Ash-Shama’il Al-Muhammadiyah, a small collection describing the Prophet (SAW)’s characteristics.
The Sunan of Nasa’i (d. 303) is a collection of about 5,700 ahadith. Imam Nasa’i was one of the major hadith scholars in the generation after Bukhari and Muslim. That is why his collection is highly regarded.
The Sunan as-Sittah is a term to refer to the six collections Sahih Bukhari, Sahih Muslim, Sunan an-Nasai, Sunan Abu Dawud, Sunan at-Tirmidhi, and Sunan Ibn Majah. That is their general order of overall authenticity.
Ibn Majah’s collection is the weakest among them, and it contains some extremely weak (or even fabricated) ahadith. The other books generally do not contain extremely weak ahadith, but can contain weak or hasan ahadith.
Some scholars said Sunan ad-Darimi would have been a better choice as the sixth collection instead of Sunan Ibn Majah, not because there are no other more authentic collections but because Sunan ad-Darimi supplements ahadith the others do not contain.
The Sahih of Ibn Khuzaimah (d. 311) is a collection of ahadith that were sahih according to Ibn Khuzaimah. Much of the collection is lost and only the first quarter is left, and that contains around 3,000 ahadith.
The Sahih of Ibn Hibban (d. 354) is a collection of sahih ahadith according to Ibn Hibban, and it is organized in a unique way similar to no one else. Ibn Hibban is however described by some as being lenient in his grading.
The Mustadrak of al-Hakim (d. 405) is a collection of ahadith where al-Hakim intended to add ahadith that are not in the Sahihayn but are still sahih according to their conditions. Many scholars criticized al-Hakim’s collection as not truly being filled with sahih ahadith. Some of the narrations in it are even graded by many scholars as fabricated!
5.2 Collections from Collections
The following are some collections that collected ahadith mentioned in preexisting collections.
So, they do not contain the author’s chain back to the Prophet (SAW) for every hadith, but they contain a reference to which collection the hadith was taken from. Usually, they include the companion who narrated the hadith as well.
Riyadh as-Saliheen of Nawawi (d. 676) is a famous collection about manners and ethics, and it derives its ahadith from the Sunan as-Sittah. It was written for non-specialists to read.
Mishkat al-Masabih of at-Tabrizi (d. 741) is a collection that encompasses most of fiqh. For every section, it first mentions ahadith in the Sahihayn, then ahadith that are hasan, then narrations that are related to the topic. He would also note which collection he got a hadith from.
Bulugh al-Maram of Ibn Hajr (d. 852) is a collection on fiqh written primarily to give evidence for the Shafi’i school but it often contains ahadith of different sides.
Arba’un is a genre of books that collect 40 ahadith on any given topic. There is a weak hadith to support this concept. The most famous Arba’un collection is the Arba’un of Nawawi which contains 40 ahadith that explain Islam in its entirety.
Mawdhū’āt of Ibn Jawzi (d. 597) is a collection of ahadith Ibn Jawzi considers fabricated, organized by topic. He mentions narrations then notes the criticism of its chains and the evidence of its fabrication.
6. Sahih Bukhari and Sahih Muslim
The scholars agreed upon the authenticity of Sahih Bukhari and Sahih Muslim generally speaking, but some did criticize individual narrations from each of them.
As for Sahih Bukhari, a few scholars criticized a handful of ahadith in Sahih Bukhari, but these criticisms were themselves responded to by many other scholars. So, it is correct to say every hadith in Sahih Bukhari is considered sahih by the vast majority of scholars.
As for Sahih Muslim, there are more ahadith in it that have been criticized, but scholars generally consider the ahadith in it authentic.
There is much overlap between the narrations of Sahih Bukhari and Sahih Muslim, but there are also many narrations that one of them mentions but the other does not. When both Bukhari and Muslim narrate a hadith in their Sahih, that hadith is called Muttafaqun Alaih (agreed upon), and that is considered the highest status of sahih. Next in status is what Bukhari alone narrates then what Muslim alone narrates.
6.2 Their Methodology
Imam Bukhari did not write an introduction or explanation about the methodology of his classification. However, Imam Muslim did write an introduction explaining his methodology, and this introduction of Muslim is studied in classes of Usul al-Hadith. Some of the topics discussed in it were mentioned in the section of Hadith Classification.
The most correct opinion is that there was not much difference in the actual principles of how to classify hadith between the two of them. The difference was on the exact application of those principles.
‘An‘anah, as mentioned before, is when a narrator narrates from someone by saying “عن”. It would be like saying “from XYZ” in English.
Some people say Bukhari and Muslim differed about ‘an‘anah and that Bukhari had the condition that there be proof of actual meeting between two narrators if the transmission was only ‘an‘anah but Muslim did not have this condition.
This claim is problematic and incorrect. None of the hadith scholars had the condition that there be proof every narrator met the narrator before him. They only required this proof if a narrator was known for being a mudallis.
Both Bukhari and Muslim organized their collections predominantly according to topics of Islam. They are first divided into “books” for general subjects, then “chapters” (baabs) for specific topics under that subject. Each chapter has one or more ahadith.
The books are largely ordered by fiqh, even though the topics in them might be more than just fiqh. For example, both of them have Books on Wudhu, Salah, Hajj, and Fasting.
They also both have Books on Iman, Qadr, Knowledge, Heart-Melting (Riqaq), Manners, Tafsir, Virtues of the Companions, and Fitan (prophecies of future events).
Bukhari has Books on Tawheed (Aqidah) and the Beginning of Revelation.
Muslim also has Books on Dreams, Piety, Repentance, Qualities of the Hypocrites, Descriptions of Qiyamah and Hell, and Descriptions of Paradise.
Bukhari wrote his own chapter titles. Muslim did not write chapter titles in his book, but the titles were most likely written by Nawawi in his Sharh of Muslim.
6.4 Asl and Shawahid
Imam Bukhari, in each chapter, might bring one or more ahadith. The first hadith he writes in every chapter is usually extremely strong and is called asl (pl. usul).
The supporting ahadith he brings after the first hadith are called shawahid (sing. shahid). Although the shawahid are weaker than the usul, they never reach the level of weak. Even sahih has levels.
Imam Muslim has the habit of writing different versions of the same ahadith to show the exact wording of different routes of transmission. The first version he quotes is the strongest, then the ones after are a bit weaker, and the last is the weakest (but not necessarily weak).
Sometimes, Muslim will quote a chain and say “He narrated the same as the previous narration” and sometimes he will say “He narrated the same as the previous narration except he changed XYZ to ABC.” He was extremely careful with different wordings.
6.5 Who Reads the Sahihayn?
Imam Muslim in his introduction states that he tried to make his book easy for normal people to read. That said, the Sahihayn are not for casual reading for three reasons.
Firstly, something people in those days might have been familiar with would be unfamiliar today, and something people today are familiar with may have been completely unfamiliar in that time.
An example of the first is many fiqh debates might have been famous in those times which are not as famous today. So, Imam Bukhari or Muslim might subtly reference one of them but a reader today would not understand.
An example of the second is some scientific knowledge which was discovered today might require a proper interpretation of a particular hadith.
Secondly, being familiar with Arabic is important if one wishes to fully understand any hadith. An Arabic word might have multiple meanings while a translation only conveys one.
Thirdly, being familiar with Usul al-Fiqh is important if one is to properly use a hadith to derive fiqh rulings. It is possible someone does not know abrogation or how to properly interpret some words of the Prophet (SAW).
That is why it is recommended to read through the Sahihayn with the aid of a teacher who is familiar with Fiqh, Arabic, and Usul al-Fiqh.
That said, some sections are fine to read casually, like the Books of Heart-Tendering. It is also fine to reference specific ahadith for the purpose of a wisdom or non-legal issue. But, to derive rulings and especially to contradict the schools of law, it is important to study with a teacher or reference a sharh of the book to properly understand it.
6.6 Mu’allaq and Mursal Narrations
The Mu’allaqaat of Bukhari are narrations in his book which he mentions without the full chain.
After mentioning his chapter title, Bukhari often mentions verses related to the chapter, mu’allaq statements by tabi’īn and sahabah about the topic, and sometimes, mu’allaq statements from the Prophet (SAW).
Because Bukhari mentions them without a chain, there is difference of opinion about whether Bukhari intended them to be sahih. Many times, he quotes the full narration with a chain in other parts of his collection. If he does not quote the full narration, it is possible he does not intend to declare it sahih in chain.
Both Bukhari and Muslim do not usually quote mursal narrations. However, they may sometimes mention a mursal narration after a hadith because the tabi’i narrator of that hadith mentioned it after narrating the hadith.  These portions of Sahih Bukhari are not necessarily sahih.
There are also some narrations in Bukhari’s book where he mentions the full chain but narrates from his teacher with “He said” or “From him” instead of “He narrated to us.” The hadith may still be sahih. As the section about ‘An‘anah mentions, if a reliable narrator narrates like this, it is considered reliable, and Bukhari is definitely a reliable narrator.
There are many commentaries and explanations on the Sahihayn.
The most famous commentary of Sahih Bukhari is Fath ul-Bari by Ibn Hajr (d. 852). Others include the commentaries of Khattabi (d. 388), Ibn Battal (d. 449), and Ibn Rajab (d. 795).
The most famous commentary of Sahih Muslim is the Sharh of Nawawi.
No full commentary of either of the books has been authored in English, however, the explanations of various ahadith in them can be found in other books, writings, and fatwas.
Some websites have English commentaries on various ahadith, like HadithEnc.com.
7. Manners of Learning Hadith
7.1 Manners of Knowledge
As with all knowledge, it is necessary to have a proper intention when learning hadith.
Whoever learns or memorizes hadith to compete with others, to get fame, to argue, or to be known as pious has an evil and sinful intention.
Whoever learns hadith to learn Allah’s religion and apply it in his life or out of love for Allah and the Prophet (SAW) has a good and rewarded intention.
Whoever learns hadith simply because he finds the subject interesting has a neutral intention. It is better for him to add a good intention to it.
7.2 Manners of Hadith
The early scholars used to treat hadith with a lot of respect because they are the words of the Prophet (SAW).
When Imam Malik was going to narrate hadith, he would first perform ghusl, wear perfume, and wear good clothes.
We should have respect for hadith in the same way.
When hearing a hadith, one should not respond to it aggressively or raise one’s voice over the narrator. Allah says:
O you who have believed, do not raise your voices above the voice of the Prophet or be loud to him in speech like the loudness of some of you to others, lest your deeds become worthless while you perceive not.
Indeed, those who lower their voices before the Messenger of Allah – they are the ones whose hearts Allah has tested for righteousness. For them is forgiveness and great reward.Quran 49:2-3
When one hears the name of the Prophet (SAW), he should regularly send salawaat on him. Allah says:
Indeed, Allah sends salawaat upon the Prophet, and His angels [ask Him to do so]. O you who have believed, send salawaat upon him and [send] peace.Quran 33:56
7.3 Weak Hadith
It is not appropriate for someone to narrate a weak hadith without identifying it as weak. Some people said this is only necessary if the hadith is extremely weak.
You should not narrate hadith you heard from people not known for carefulness in hadith without verifying them.
It is reported that Umar ibn al-Khattab said, “It is enough of a lie that a man narrates everything he hears.” (Introduction of Sahih Muslim)
When narrating a hadith you heard from someone, say “I heard someone say the Prophet said XYZ.” When narrating a hadith you do not remember well, say “I heard someone say, but I do not remember well, that the Prophet said XYZ” or something similar and not directly say “The Prophet said XYZ.”
When narrating a hadith that is not well-known to be sahih, you should say “It is reported that the Prophet said XYZ” or something similar.
If you narrate a hadith by meaning, make it clear. Say something like “It is reported that the Prophet said along the lines of XYZ.”
7.4 Deriving Fiqh
It is not appropriate for someone to derive law from ahadith, especially when they allow for multiple interpretations or abrogation without knowing all the ahadith on the topic and knowing the interpretation of the different scholars.
It is possible a hadith seems clear and it is abrogated by another hadith or is elaborated by another hadith or there is a verse in the Quran that affects it.
7.5 Who to Teach Hadith?
It is not appropriate for someone to narrate difficult to understand ahadith to someone with little knowledge and iman except in the proper context with a proper explanation. It is especially not appropriate to do so in debate and argument.
If one does not take care, he will misguide people or lead them to deny the Prophet (SAW).
Teach and narrate ahadith to people according to their level of knowledge. 
8. Difficult Ahadith
8.1 Meaning of Mushkil
Mushkil ahadith are those ahadith that are difficult to understand, seem apparently problematic, or astonish people.
Ishkal (being mushkil) can be due to several reasons:
- Apparent contradiction with the Quran
- Apparent contradiction with other (more authentic) ahadith
- Apparent contradiction with other sources of knowledge like science and history
- Apparent contradiction with a person’s preconceived ethics
- Apparent contradiction with a person’s preconceived or cultural notions
8.2 Mushkil Due to Quran or Another Hadith
If there is a contradiction with the Quran or another authentic hadith, the contradiction is only apparent and never real.
You should first see if there is a possible interpretation of the two that can get rid of the ishkal. If there is an interpretation without difficulty, follow that interpretation.
Then, you should see if it is possible one abrogates the other. If it is possible, you should interpret it as abrogation and consider the earlier one abrogated.
If neither combination nor abrogation are possible, you should see if one of them is stronger than the other. If there is, you should follow the stronger one and consider the weaker one inauthentic.
If nothing is possible, you should stay silent on the matter until you find a way out.
8.3 Types of Hadith
The Prophet’s statements can be divided into two categories:
- Statements about religion or when he clearly attributes something to revelation
- Statements about the world when he does not attribute it to revelation
When the Prophet (SAW) talks about religion, it is definitely correct. When the Prophet (SAW) talks about the world without reference to revelation (like medicine), it is not necessary it is from revelation or that he is correct. He could be basing his statement on the general knowledge of the time.
The Prophet (SAW) said, “If it is something from the affairs of your world, you have your expertise with it. If it is something from the affairs of your religion, then [refer] to me.” (Sunan Ibn Majah)
There are some narrations where it is unclear whether it came from revelation or not. In that case, one should estimate to the best of his ability. 
8.4 Muskhil Due to Science
Science has theories which can be very strongly proven or weakly proven.
If a hadith of the first type is very strong and a theory has room for doubt, the hadith should be preferred.
If a hadith contradicts a strong theory of science, one should first see if there are possible interpretations of the words of the hadith that match the theory.
If the hadith does not allow any other interpretation, one should see if there is weakness in the hadith itself or that exact wording of the hadith. If there is another authentic wording of the hadith that does not contradict the scientific theory, that should be preferred.
If the hadith has some weakness in it and it contradicts a strong theory, it is possible to consider the hadith weak and accept the theory. If the hadith is very strong and the theory is also strong and there is no reconciliation possible, one should stay silent on the matter but prefer the hadith until some evidence comes to light.
If a hadith is of the second type, only being about the world with no reference to revelation or religion, then there is not much problem in preferring science over it if it is difficult to combine the two. It may simply be something the Prophet (SAW) said based on the knowledge of the time rather than revelation. 
8.5 Mushkil Due to Custom or Ethics
If an authentic hadith contradicts people’s customs or ethics, their customs and ethics are rejected in favor of the hadith.
For example, the narration of Aisha (RA) being nine when she married the Prophet (SAW) contradicts modern ethics. However, the narration is completely authentic and one cannot reject it because of ethics.
Another example is the narration of Musa (AS) taking a bath then a rock running away with his clothes. This narration surprises some people and goes against their customs so they reject it. But, their customs are rejected in favor of the hadith.
That is because Allah and the Prophet (SAW) are not limited by the customs and ethics made up by human minds. They are the deciders of true ethics.
8.6 Sources to Resolve Ishkal
The resolution of mushkil narrations relative to Quran and other ahadith has many books. The first source is to see the books of commentary. Some scholars wrote books specifically on this topic like Imam Tahawi wrote Sharh Mushkil al-Athar.
There are usually many online articles and fatwas resolving mushkil narrations relative to science. Be careful to read only those written by people who have a proper methodology and not by hadith-skeptics or hadith-deniers who reject ahadith at the slightest whim or give weak interpretations of science or hadith.
- See “Does Quran say to Follow the Sunnah?” for more verses with detailed explanations.
- For example, see the title of this article.
- The correct view is that no specific number defines mutawatir and that it is contextual. Whatever number rules out the possibility of collaboration or coincidence is mutawatir.
However, some gave specific numbers like four, five, seven, ten, twelve, forty, seventy, and more. All of these numbers are not necessary in the definition and the latter two are exaggerations. As long as there are enough narrators in a way that rules out anything but truth, that is mutawatir.
- Shuzuz is when an otherwise reliable narrator contradicts someone even more reliable than him, and nakarah is when an unreliable narrator contradicts someone more reliable than him. A hadith with shuzuz is called shāz, and a hadith with nakarah is called munkar.
- A subtle defect is just a problem in one of the first four conditions which is subtle to notice. For example, a hadith can have a disconnected chain that looks at first glance to be connected.
- Many of the more diligent hadith scholars in the later generations are careful to note the exact word they do not remember accurately when they narrate something they do not remember fully.
- An example of difference in the general rule is how the scholars differed about what to do when a weaker narrator mentions an addition to a hadith that a stronger narrator did not mention. Some said the addition is authentic as long as the narrator is strong.
An example of difference in the specific application is how the scholars might differ about the exact level of reliability of a person. Some might say his ahadith are sahih and others might say they are just hasan. They might also differ about how he compared to another narrator: stronger or weaker.
- Abdullah ibn Amr said, “I used to write everything I heard from the Messenger of Allah, intending to memorize it. (Some of) the (Muslims of) Quraysh prohibited me saying, ‘Do you write everything that you hear from him while the Messenger of Allah (ﷺ) is a human being who can speak in anger and pleasure?’ So, I stopped writing, and mentioned it to the Messenger of Allah. He signaled with his finger to him mouth and said: ‘Write, by Allah, nothing comes out of it except truth.'” (Sunan Abu Dawud, Sahih)
Abu Hurairah said, “No one has more hadith from the Prophet (SAW) than me except Abdullah ibn Amr because he used to write while I did not write.” (Sunan Tirmidhi, Sahih)
Abu Hurairah (RA) wrote after the Prophet (SAW), and some of his collection still exists in the Sahifah of Hammam, Hammam being one of his students who copied the narrations into his book. It is one of the only full collections directly from a companion to reach us without being subsumed by other collections. It has 137 narrations, most of which are also included in Sahih Bukhari.
- See previous footnote.
- For the same reason as the companions, but there was an additional reason. People also started writing the opinions of scholars, and they did not want people to write their opinions down.
- An example is the hadith about the beginning of revelation in Sahih Bukhari. At the end of it, Zuhri (a tabi’i and one of the narrators) adds a story about the Prophet (SAW) becoming so sad when the revelation stopped that he considered suicide. Zuhri says, “The revelation stopped for some time until the Prophet (SAW) became so sad according to the information that reached us [that he did this or that].” However, Zuhri is not a companion and thus cannot be the direct source of this information, and Zuhri is also notoriously unreliable when he does not mention his sources. So, this part does not have much authentic basis. And Allah knows best.
- For example, do not narrate the hadith about cure being in both wings of a fly to someone who has doubts about Islam’s relationship to science without reason.
- For example, when the Prophet (SAW) says something that is extraordinary or almost miraculous about the world even to the Arabs at the time, then it should most likely be understood as being from revelation.
- For example, many ahadith related to medicine have no reference to revelation.