The scholars did an immense amount of research on each narrator, their lives, their teachers, their students, and their narrations to figure out if they were reliable and trustworthy.
This is the level of importance they placed on making sure the Sunnah of the Prophet ﷺ would remain completely preserved. They set two different general conditions that had to be met by narrators to be considered reliable, and those were:
The five conditions for ʿAdālah are:
- The person must not have ever been known to lie.
- The person must not have even been accused of lying.
- The person must not be known to sin openly.
- The person cannot be “unknown”.
- The person cannot be someone who is known for innovations in the religion.
- The person must not be neglectful or have oversight.
- The person must not have frequent errors.
- The person must not disagree with reliable authorities and narrators.
- The person must not be known for misunderstandings.
- The person must not have bad memory.