with the initials of whichever of the six canonical Imams have transmitted it. The compilation also contains narrations that are not found in the Six Books; these additional reports come from Razīn, and in Jāmiʿ al-Uṣūl their distinguishing mark is that no symbol appears before them.

Ibn al-Athīr organised Jāmiʿ al-Uṣūl as a series of thematic “books” set out in alphabetical order, and within each one he includes whatever relates to its topic.

If a student wishes to locate a particular ḥadīth in the Six Books and knows its wording, he can do so by searching for it in the section where it is most likely to occur in those collections. Thus, if the narration concerns faith, for example, he should look in the Book of Faith in the two Ṣaḥīḥs and the Sunan. Should he know the name of the Companion who transmitted the report, he may consult Tuhfat al-Ashrāf by al-Ḥāfiẓ al-Mizzī, for that work indicates where the ḥadīth appears in the Six Books; alternatively, he can turn to the book Dhakhāʾir