What is the ruling on paying off a debt borrowed in dollars with installments valued in Saudi riyals?

The principle is that the loan should be repaid in the same currency in which it was taken. It is permissible to agree on another currency at the time of repayment, at the exchange rate of that day. However, there are prohibited forms in this transaction:

1. Agreeing at the time of contracting the loan to repay in another currency: This is prohibited because it is the sale of a present currency for a deferred currency, which falls under riba al-nasi’ah (interest of delay). The exchange of different currencies requires immediate possession (taqabud). 2. Agreeing at the time of repayment on another currency at the exchange rate of the day the loan was contracted: This is also prohibited, due to the Prophet's (peace be upon him) prohibition of taking more than the exchange rate of that day, and because it involves profiting from something that has not entered into the guarantor's (lender's) possession. 3. Agreeing at the time of repayment on another currency and separating before full possession: This is impermissible due to the requirement of taqabud (mutual possession) in currency exchange.

It is permissible to repay the loan in installments, and to agree, at the time of each installment's repayment, to take it at the exchange rate of that day with immediate possession (taqabud).