—that of serving as money. The same applies to dirhams, for the Prophet, may Allah bless him and grant him peace,

“forbade selling one dirham for two dirhams, or one dinar for two dinars,”

and “forbade exchanging dirhams for dinars except hand to hand.”

The prohibition of deferred exchange is unanimously agreed upon by the Muslim community. The prohibition of unequal exchange, even when conducted hand to hand, is established by authentic hadiths and upheld by the majority of the Muslim community. Yet the legislation of Allah and His Messenger embodies profound wisdom, perfect blessing, and universal mercy that may escape many scholars. Scholars, both early and later, have disagreed over many “questions concerning usury.”

They have disagreed over the basis for prohibiting unequal exchange of the six commodities: gold, silver, wheat, barley, dates, and salt. Is it equivalence—namely, measurement by volume and weight? Or is it monetary function and edibility? Or is it monetary function and equivalence, together with edibility, staple food, and what complements it? Or does the prohibition have no underlying legal rationale, with the ruling confined to what the text expressly mentions? These are well-known positions.

The “first” is the position of Abū Hanīfah and of Ahmad according to the best-known reports from him. The “second” is the view of al-Shāfi‘ī and of Ahmad according to one report. The “third” is Ahmad’s view according to a third report, which Abū Muhammad preferred. Mālik’s view is close to this, and this position is stronger than the others. The “fourth” is the view of Dāwūd and his followers, and it is also reported from Qatādah. Ibn ‘Aqīl favoured this view in his Mufradāt and deemed weak