It is invalid to sell a ribā-liable commodity for its own kind while adding—on either or both sides of the deal—something from a different category, such as exchanging one mudd of ʿajwa dates together with a dirham for the like of both, or trading a dinar and a dirham for a single dinar. It is, however, legitimate to say: “Give me, for half of this dirham, silver, and for the other half, copper coins.”

It is likewise permissible to exchange gold for gold or silver for silver, provided the two amounts are identical in weight—not merely by count—on condition that each party takes possession before they part company, and that any shortfall in one of the two currencies is made good according to the market rate of the day.