and neither custom nor usage may be invoked to establish a legal ruling unless no scriptural text exists for the point under consideration. If, however, custom conflicts with the scriptural evidence only in some of its particulars, or if the scriptural proof is derived by analogy, then prevailing custom is deemed a qualifier of the text, and analogy is abandoned in its favor.

General rule: Whenever the Sharia speaks of a matter in absolute terms without prescribing a specific standard, and the language itself provides none, the criterion is referred to customary practice. A case in point is ḥirz (secure keeping) in theft: its limit is fixed by custom, for neither the Sharia nor the language defines it, and it differs according to the type of property and the circumstances involved.