ʿUrf was first recognized by Abū Yūsuf (d. 182/798), an early leader of the Ḥanafī school, though it was considered part of the sunnah, and not as formal source.
[2] The "maxim" that custom is an authoritative source for Islamic law "appears in the Quran and Hadith".
According to some sources, ʿurf holds as much authority as 'ijma (consensus), and more than qiyas (legal reasoning by analogy).
[4] In the application of ʿurf, custom that is accepted into law should be commonly prevalent in the region, not merely in an isolated locality.
Jurists also tend to, with caution, give precedence to custom over doctoral opinions of highly esteemed scholars.