The Prohibition of Riba al-Fadl

This hadith from The Book of Musaqah in Sahih Muslim (1585) establishes a foundational principle in Islamic commercial law, explicitly prohibiting Riba al-Fadl (the riba of excess). The Messenger of Allah ﷺ forbade exchanging gold for gold or silver for silver unless it was equal for equal, hand to hand. Selling one dinar for two dinars, or one dirham for two dirhams, is a direct violation, as it involves an increase of the same commodity in a spot exchange.

Scholarly Commentary on the Ruling

The wisdom behind this prohibition is to close all avenues leading to Riba an-Nasi'ah (the riba of delay), which is the core of usury. If an increase were permitted for immediate exchange, it could easily be used as a legal trick (hilah) to justify a deferred exchange with interest. The scholars have extended this ruling by analogy (qiyas) to the six commodities mentioned in the famous hadith of the six items: gold, silver, wheat, barley, dates, and salt. When these are exchanged for the same type, they must be equal in measure and handed over immediately.

This ruling applies specifically to transactions of homogeneous commodities used as a monetary standard or staple food. The underlying cause ('illah) for gold and silver is their function as a monetary standard (thaman). For the food items, it is their nature as measurable/weighable staples (ta'am and mithli). Therefore, the prohibition extends to any items that share the same underlying legal cause.

Practical Application and Exceptions

In a practical modern context, this means one cannot sell a gold bracelet for a greater weight in raw gold, or a specific type of date for a larger quantity of the same type of date. The exchange must be equal and simultaneous. The prohibition is lifted if the items are of different kinds. For example, it is permissible to sell one dinar (gold) for multiple dirhams (silver) or to sell wheat for a different type of grain, as long as the exchange is hand-to-hand (spot transaction) to avoid the element of delay and uncertainty (gharar) that characterizes usury.