"عُرف"（ʿUrf）是社会所习惯的事物，已成为其习惯，并在言语和行为上遵循，它代表社会反复形成的惯例。

The ‘Urf is what the society is accustomed to, made habitual and proceeds upon in its life in terms of speech and action and it represents the repetitive custom of the society.

一些穆斯林的法学家，例如马立克学派（Al-Maalikiyah）和哈乃斐学派（Al Hanafiyah），将其视为在没有经文（Nass）的情况下，对某一具体现实立法（Tashree'）的证据（Daleel）之一。然而，就非穆斯林而言，"习惯"（'Urf）是人定法的一个根本和主要的来源。

Some of the Fuqahaa of the Muslims like Al-Maalikiyah and Al Hanafiyah counted it as a Daleel for Tashree’ (making legislation) in the case where there is no Nass (text) (applying) upon a (given) reality from amongst the realities. However, the ‘Urf in respect to non-Muslims represents a fundamental and main source for the man-made law.

西方人总体上是依据“乌尔夫”（即习惯法），或依据他们在风俗和传统方面已经习以为常的做法，来制定规范其生活和社会关系的法律，并以此处理他们之间出现的问题。

The Westerners, in general, set the laws that regulate their life and their societal relationships and treat the problems arising amongst them based upon the ‘Urf or based upon what they have become accustomed to in terms of customs and traditions.