and ninety riyals in metal coinage. The difference between this case and the previous one is that this is an exchange of different kinds: in reality, each of these is a distinct kind intended in its own right. Although we say that this paper riyal corresponds to this metal riyal in its official value, that does not mean that it is equal to it in its actual value. This is the position of the madhhab, and it was also the preferred view of our teacher, Abd al-Rahman ibn Sa‘di, may Allah have mercy on him: namely, that it is permissible to exchange coins for one another even with disparity, and even if possession is delayed, provided that the transaction is not deferred. Thus, if I say, “I sold you one hundred dollars for four thousand riyals, payable in one year,” this is not permissible according to him. But if he says, “I sold you one hundred dollars for four thousand riyals,” and neither of us takes possession, then this is valid according to him.
However, this view is open to question, because it is based on treating this as analogous to coinage; and according to the madhhab, coinage is subject neither to delay-based ribā nor to surplus ribā. Another view concerning coinage is that delay-based ribā applies to it, but not surplus ribā. This is the stronger view, because coinage in reality has only an official value; paper currency is therefore analogous to coinage. This is a middle position. Another view holds that both delay-based ribā and surplus ribā are prohibited in it. Yet another view is that dealing in it is altogether impermissible, and that transactions involving it are unlawful, because it is a debt owed by the government. Thus, if you buy or sell with it, you have bought a debt for a debt. However, one may deal with it out of necessity, restricted to the extent of that necessity.
The view that appears strongest to me is that delay-based ribā applies to it, but not surplus ribā. Therefore, the parties may not separate before taking possession. Yet they now permit a person to sell eight paper notes and eight qirsh for one silver riyal.