—of the two? Yet another scholar may know that the report in question belongs to the ḥadiths he transmitted while fully reliable.

Another cause is that the transmitter may have forgotten the report and therefore never mentioned it again, or he may deny ever having narrated it, thinking such denial a defect demanding its rejection. A different scholar, however, will still treat the report as a valid proof; this issue is well known.

A further cause is that many scholars of the Ḥijāz hold that no ḥadith related by an Iraqi or a Syrian is admissible evidence unless it has a corroborating origin in the Ḥijāz. One of them even said, “Treat the reports of the Iraqis like the reports of the People of the Book: do not affirm them and do not deny them.”

Someone asked another scholar, “Is the chain Sufyān → Manṣūr → Ibrāhīm → ʿAlqamah → ʿAbdullāh authoritative?” He replied, “Only if it has a basis in the Ḥijāz.”

They hold this view because they believe that the people of the Ḥijāz preserved the Sunnah so completely that nothing escaped them, whereas the Iraqi transmissions contain inconsistencies that require caution.

Conversely, some Iraqis maintain that the ḥadiths of the Syrians are not to be used as proof, although most scholars refuse to declare them weak on that account alone.

The governing rule, however, is that whenever the isnād is sound, the ḥadith is authoritative—whether it is Ḥijāzī, Iraqi, Syrian, or from anywhere else.