Although we have many Aḥādīth, not all of them are authentic. Some may be narrated by weak narrators, some may be narrated by strong narrators and have mistakes, and some may be complete fabrications.
Assuming that we wish to know how the Prophet Muḥammad ﷺ practiced Islām, how do we we know which Aḥādīth from him are authentic and reliable and which are not?
The scholars of Ḥadīth have created a process to do so, based on rigorous analysis of each narrator of the Ḥadīth, heavy research of the narrators, and a detailed examination of the text of the Ḥadīth.
The scholars of Ḥadīth have separated Aḥādīth into three categories: Ṣaḥīḥ, Ḥasan, and Ḍaʿīf. Let’s look at how each of them are defined:
Ṣaḥīḥ means “correct/authentic.” For a Ḥadīth to be considered Ṣaḥīḥ, there are 5 major conditions that have been listed by the scholars.
1. All the narrators must meet the conditions of ʿAdālah (moral uprightness). This means that they are all trustworthy and honest people. You can read more about this here.
2. All the narrators must meet the conditions of Ḍabt (accuracy). This means that they all must be people who have good memory and are not known for making mistakes. You can read more about this here.
3. The chain of narration for the Ḥadīth must connect, meaning no narrators are skipped.
4. The Ḥadīth must not truly contradict the Qur’ān or other authentic Aḥādīth. If two Aḥādīth appear to be authentic but contradict, then there is a reconciliation process.
5. The Hadith must have no hidden defects or faults.
Ḥasan means “fair/good.” A Ḥadīth is considered Ḥasan if it meets all the conditions of Ṣaḥīḥ but has one or a few narrators in the chain that are known for issues with Ḍabt (accuracy). We can accept the Ḥadīth and learn lessons from it, but we are wary of possible mistakes.
Ḍaʿīf means “weak.” A Ḍaʿīf Ḥadīth is one that doesn’t meet the conditions for Ṣaḥīḥ or Ḥasan. There are numerous types of Ḍaʿīf Aḥādīth, depending on the level of weakness in them. Some are fine to use as evidences, while others should be entirely left off due to a great level of weakness.