Selling dollars for Saudi riyals on a deferred basis

Question:
Honorable Shaykh, may Allah grant you success. A man asks about buying one thousand dollars for two thousand dollars on a deferred basis, with the payment between them to be in Saudi riyals. Is this permissible?

Answer:
No, this is not permissible under any circumstances. Selling currency for currency must be immediate; this is not permissible, whether the currencies are of the same type or different. This is riba al-nasi'ah (usury of deferment). If the currency is of the same type, then both riba al-nasi'ah and riba al-fadl (usury of excess) are present. If one buys one thousand dinars, or one thousand dollars, for one thousand five hundred dollars, that is riba al-fadl and riba al-nasi'ah. If one buys one thousand dollars for fifty thousand Saudi riyals on a deferred basis, that is riba al-nasi'ah. So it is established that this is riba al-nasi'ah.