for others does not involve usury. Thus, it would be permissible for me to take one hundred dollars from you in exchange for four hundred riyals payable after one year, or one thousand riyals in exchange for one thousand two hundred payable after one year, because usury does not apply to them. This view, however, is open to question, for people regard these currencies as equivalent to money, distinguishing between them only slightly.

Some scholars have said that usury of delay applies to them, but not usury of excess. Thus, if one currency is exchanged for another while taking possession is delayed, this is unlawful, whether the exchange is equal or unequal. But if they are exchanged and possession is taken during the contractual session, this is permissible even if the amounts differ.

This is the view closest to correctness in this issue, especially when the currencies are of different kinds.

Question: When exchanging metal riyals for paper riyals, is an excess in one amount permissible?

Contemporary scholars have differed over this. Some held that it is unlawful, because the metal riyal is the same as the paper riyal: there is no difference between the two, the intended currency is one and the same, and the state has assigned them equal nominal value.

Others held that it is permissible, because there is a difference between them: they are in fact different kinds and differ in value. Their equality in purchasing power is only due to the state’s valuation. Evidence for this is that if you brought one hundred kilograms of this metal and one hundred kilograms of paper, would their values differ or not?

The answer is that they would differ. Iron is purchased for its own intrinsic value, whereas paper would have no value whatsoever were it not for the value assigned to it by the state.

They said: Since the kinds differ in reality and in value, an excess is permissible.