Abu Ahmad ibn ʿAdi said, “With respect to narrations other than those from al-Zuhri he is sound, whereas in what he transmits from al-Zuhri he relates matters in which he differs from the people.” (1)

They therefore explain that there is no contradiction between the verdict of those who graded him weak and that of those who declared him reliable; the scholars who deemed him reliable did so for his narrations other than from al-Zuhri while still weakening him in what he reports from al-Zuhri. This question is separate from the issue of conflicting criticism and praise, though someone of limited knowledge may imagine it to be the same and set the criticism of one scholar against the commendation of another. Rather, the matter here is different: it concerns accepting a narrator’s ḥadīth when he relates from certain teachers and declining to use the very same narrator as proof when he relates from others. (2)

The case of Ismaʿil ibn ʿAyyash is analogous: according to the leading authorities in this field he is an authoritative source when narrating from the Syrians, the people of his own land, but not authoritative in what he transmits from the Hijazis, the Iraqis, or anyone outside his region. (3)

Likewise, some scholars regarded Qabisah as weak in his narrations from Sufyan al-Thawri (4), yet still used him as evidence in narrations from other shaykhs, exactly as Abu ʿAbd al-Rahman al-Nasaʾi did. (5)

This is the method of the discerning hadith specialists, the physicians of its hidden defects: they cite a man’s narration as proof when he reports from a teacher whose narrations he is known to transmit often and preserve accurately,