Is it permissible to repay the debt of the deceased uncle in Algeria to his heirs in France in euros, knowing that it was in Algerian dinars, and is this done at the parallel market exchange rate for each installment at the time of repayment?

It is permissible for a Muslim to repay a debt with a currency different from the one in which it was borrowed, provided two conditions are met: First, that this was not stipulated at the time of the loan agreement. Second, that the repayment is made at the exchange rate on the day of repayment. This is based on the saying of the Prophet, peace and blessings be upon him: "Gold for gold, silver for silver... like for like, equal for equal, hand to hand. But if these types differ, then sell as you wish, if it is hand to hand." It is also permissible to divide the debt into installments, with each installment paid at the exchange rate on the day of its payment.