Is it permissible to lend the state a sum in dollars to be repaid in the local currency after five years at the exchange rate on the day of repayment, similar to the case of customs exemption for cars by paying a deposit in dollars and receiving it back in the local currency after five years?

It is permissible for the lender and the borrower to agree, at the time of repaying the loan, that it be repaid in another currency, provided that the agreement is made on the day of repayment and not before, and at the exchange rate of that day. It is not permissible to stipulate this at the time of contracting the loan, because it is considered a deferred exchange, and an exchange is only valid with immediate possession. Nor is it permissible to agree to record the debt in a specific currency, equivalent to its value in gold or another currency, as a liability on the debtor, such that he is obliged to repay it in that manner.