and indeed the most subtle of them; no one can master it except one whom Allah has endowed with a penetrating insight, vast retention, complete knowledge of the ranks of transmitters, and a strong command of both chains of transmission and textual contents. For that reason only a handful of experts in the field have ventured to speak about it—such as ʿAlī ibn al-Madīnī, Aḥmad ibn Ḥanbal, al-Bukhārī, Yaʿqūb ibn Shaybah (1), Abū Ḥātim, Abū Zurʿah, and al-Dāraquṭnī.

At times, however, the wording adopted by the critic (muʿallil) may be too concise to establish decisive proof for the claim he advances (2), just as happens with a money-changer (3) when appraising a dīnār or dirham (4).

[Interpolated Chains and Their Subdivisions]

Then comes contradiction (mukhālafah), which is (5) the seventh category. If it occurs because the order of the chain has been altered—that is, the sequence of the isnād—then the occurrence (6) of that alteration (7) is (8) called mudraj al-isnād (an interpolated chain). Mudraj al-isnād is further divided into several kinds:

First: A group of transmitters relate (9) the ḥadith through different isnāds; a subsequent narrator then reports it (10) from them, merging all the versions into a single isnād (11) selected from those various chains, without pointing out the discrepancies.