Dear brother in Islam, thanks for contacting us with this question, and we really commend your keenness to get acquainted with the teachings of your religion, Islam. May Allah help us all stay firm on the Right Path, Amen.

As regards your question, the following is the fatwa issued by Dr. Monzer Kahf, a prominent Muslim economist and counselor:

Contracts do not have to be written, between brothers/sister and strangers. Contracts may be verbal and/or written, but a contract is a definite relationship between its parties. A loan is a contract, it is due for repayment at exactly the same amount and kind the way it was contracted (given). If the contract happens to be a loan of a certain quantity of gold, then the repayment has to be in the same quantity of gold, for gold here is the subject of the contracted. If it’s contracted in Pakistani Rupees it is due for repayment in Pakistani Rupees, and if it is kilos of onion then it has to be settled in kilos of onion too.

But we have to bear in mind that in lending, one is always required to return the same quantity of the same item. Was the contract is Rupees? From what you described it seemed so because throughout the fifteen years everybody knew that she gave him a loan of 22000 Rupees, not so many grams of gold.

Two point may arise here. 1) the item exists no more; and 2) there is a huge price difference between the time of giving a loan and the time of repayment. As for the point No 1: if the item given as a loan does not exist at all in the market e.g., a currency that has been cancelled by the government like the case with the Majidi of the Ottoman Empire or old French Franc. Payment in this case must be made in accordance with the value of that item at the time it ceased from existence, because that was the last chance a loan could be paid back (according to Shari’ah a loan is an act of goodness and consequently it can be called back at any time, so the lender could have called it back at that moment) and there are views that argue for the time the loan is given and the time the loan is repaid ( notice the last opinion is contradictory because the assumption is that at the time of repayment the item does not exist, how can it have a value?!)

Two: if there is a huge price difference, this point stirs controversy among scholars, and the OIC Fiqh Academy has failed to solve the matter despite discussing it for several years. The principle remains that repayment is due in the same quantity of the same item as much as it makes sense, even with differences in prices. But when the value difference is huge, the best opinion is that suggested by Imam Ibn `Abdeen in his book Al-Hashyah, indicating that compromise and reconciliation should be struck on this between the parties, even if it were to be imposed by the court because there are many personal circumstances that may affect the repayment.

Lastly, generous repayment is outside the obligations of the contractual relationship, and it is recommended by the Prophet Muhammad, peace and blessings be upon him. It implies giving some extra amount at the time of repayment. Generous repayment in this case is to pay at least the price of the same amount of gold, Rps 60000, or even more, if it is affordable by the brother.”