Ibn ʿAbd al-Barr went even further, saying, “Every bearer of knowledge who is known for his diligence in it is to be presumed upright so long as no fault has been established against him.” This statement, however, is not acceptable.

Third: A narrator’s precision is ascertained when, in most cases, his reports are in accord with those of the trustworthy, highly accurate transmitters. An occasional divergence does not harm him, but should such divergences increase, his precision is compromised and his transmissions are no longer relied upon.

Fourth: According to the sound and widely held view, an endorsement of reliability (taʿdīl) is accepted even if the reason for it is not given, whereas disparagement (jarḥ) is not accepted unless its cause is specified. As for the works of jarḥ and taʿdīl that record a criticism without mentioning its basis, their benefit is to make us pause concerning the narrator in question; if we investigate his case, the suspicion is removed, and confidence in him is attained, we accept his ḥadīth. There are several such narrators in the two Ṣaḥīḥs.

Fifth: The correct opinion is that both jarḥ and taʿdīl may be established by the testimony of a single critic or endorser, though some require two. When both criticism and endorsement pertain to a narrator, the criticism takes precedence; others hold that if the endorsers outnumber the critics, the endorsement prevails. If someone says, “A trustworthy person informed me,” or the like, this is not sufficient according to the sound position, although some deem it adequate; and if the speaker is a scholar, some investigators consider it enough for those who follow his school. When an upright narrator transmits from someone he explicitly names, this does not, according to most scholars—and this is the stronger view—amount to an endorsement of that named narrator, though some count it as such. Likewise, a scholar’s acting upon or issuing a fatwa in accordance with a ḥadīth he has transmitted is not a conclusive judgment of its authenticity, and his failure to act upon it is not a flaw either in the ḥadīth or in its transmitter. Allah knows best.

Sixth: Narrations conveyed by a person whose integrity is unknown both outwardly and inwardly are not accepted by the majority of scholars.