For this reason, if a man swears that he will pay someone his due the following day, then gives him a substitute, he has fulfilled his oath according to the sounder of the two views. There is disagreement as to whether the Prophet’s prohibition on selling foodstuffs before taking possession of them applies only to selling them to someone other than the original seller. Those who explain the prohibition in terms of successive liabilities extend it to this case as well. Others explain it as ensuring that the buyer receives his purchase in full and that the seller’s attachment to it is severed, so that, upon seeing the buyer make a profit, the seller will not seek to rescind the sale or withhold delivery. They apply this rationale to a heap of foodstuffs before it is moved, even if possession has already been taken. This rationale does not apply when the goods are sold back to the original seller.

Moreover, selling the goods back to the original seller resembles cancellation by mutual agreement. According to one of the two scholarly views, such cancellation is permissible before possession is taken. Is cancellation by mutual agreement a rescission or a sale? There are two views, both reported from Ahmad. If we say it is a rescission, it is permissible only in exchange for the equivalent of the original price. If we say it is a sale, there are two views on this. As for a debt owed under a salam contract, cancellation by mutual agreement is permissible without dispute.

It is therefore clear that the rules concerning a debt owed under a salam contract are less stringent than those governing sales of specifically identified goods. Most scholars do not permit selling purchased goods back to their seller before the buyer is able to take possession of them, yet they permit cancellation by mutual agreement in the case of a salam debt. Accepting a substitute for that debt is likewise permissible, just as cancellation by mutual agreement is permissible. However, it constitutes such a cancellation only if he takes back his original capital or its equivalent, even if accompanied by an additional amount. If he sells the debt for something else, this is not cancellation by mutual agreement; rather, it is a settlement that has the character of selling something not yet received.

Ahmad permitted selling a debt owed under a salam contract to the recipient of the advance payment, following Ibn Abbās; and Ibn