Some scholars compiled works devoted to trustworthy or weak transmitters. Important examples include the critical collections of al-ʿIjlī, Ibn Ḥibbān, and Ibn Shāhīn, alongside Ibn ʿAdī’s work on weak narrators.
Inclusion in a specialized collection is significant, but its meaning depends on the author’s criteria, terminology, and the judgments of other critics. An entry should not be treated as an unqualified final ruling.
Example: if one authority lists a transmitter among trustworthy narrators and another discusses weakness, the reason for the difference and the evidence for the specific report require closer study.