[1] ʿIlm ar-rijāl is synonymous with what is commonly referred to as al-jarḥ wa al-taʿdīl (discrediting and accrediting) – the criticism and declared acceptance of hadith narrators.
[note 1][2] Ali ibn al-Madini, an early authority on the subject, said, "Knowing the narrators is half of knowledge.
"[4] He then explained that any criticism directed at a narrator was permissible due to the "maintenance of the Shariah, purging it of any mistakes or misinformation".
[4] Stressing the importance of biographical evaluation, Ali ibn al-Madini, an early authority on the subject, said, "Knowing the narrators is half of knowledge.
"[note 2][3] The following Qur'anic verse established a general principal in biographical evaluation:[5] "O you who believe, if a wrongdoer should approach you conveying information, then verify that so as not to fall into ignorance thus regretting what you have done.
[5] Evaluating the narrators of hadith began in the generation following that of the Companions based upon the statement of Muhammad Ibn Sirin, "They did not previously inquire about the isnad.
The first, uprightness (al-ʻadālah), is defined as the ability an individual possesses to adhere to moralistic decorum (al-taqwā) and maintaining proper social graces (al-murūʼah).
Precision in memorization (ḍabṭ al-ṣadr) refers to the ability to retain the specified information, recalling and conveying it at will.
A system of terminology developed to codify the standing of each narrator, with some variation in usage of terms between the individual evaluators.