When the price is unknown in a salam sale

Question

Question: A person wants rupees as a loan and says: “After two months, after the rupees (?), I will give wheat at four seers (a unit of weight, ≈ 0.93 kg) more than the rate of that time, and I will give the genuine, customary (?).” Is it permissible to take and give a loan in this way and then to repay it in this same way?

Answer

Stipulating here “I will give four seers more than the rate of that time” vitiates the sale (renders it fasid), because this is a salam sale (bayʿ salam — a sale with the price paid in advance and delivery of the goods deferred), and its condition is that the rate be fixed at that very time, i.e.

Source: Fatawa Mahmudiyya

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