His statement, “and a lease”: an example is that I sell you this house for one hundred thousand, on condition that you lease your house to me for one year. The contract is invalid because it combines two contracts.

His statement, “and currency exchange”: for example, one says, “Sell me your house for one hundred thousand.” The other replies, “Yes, on condition that you exchange these dinars of mine for dirhams.” In this case, both the sale and the currency exchange are invalid. The evidence cited is that the Prophet ﷺ “forbade two sales in one sale” (1), and said: “Whoever makes two sales in one sale is entitled to the lesser of the two prices, or else it is usury” (2).

However, adducing this evidence here is incorrect, for the Prophet ﷺ only forbade two sales in one sale and said, “He is entitled to the lesser of the two prices, or else it is usury.” This does not apply to the case mentioned. Rather, it applies to the previously mentioned ʿīnah transaction: a person sells something at a deferred price, then buys it back for cash at a lower price. Here we say: this is two sales in one sale, because the item sold is one while the contracts are two. This is why he said, “He is entitled to the lesser of the two prices, or else it is usury.” Thus, if he sells it for one hundred on deferred payment and buys it back for eighty in cash, we say: either you take nothing from the buyer beyond the excess and accept the lesser amount—namely, eighty—or, if you take the excess, you have fallen into usury, because the Prophet ﷺ said: “He is entitled to the lesser of the two prices, or else it is usury.”