said:

“It is not lawful to combine a loan with a sale, to impose two conditions in a sale, to profit from something for which one has assumed no liability, or to sell what one does not have.”

Al-Tirmidhī said: “This is an authentic hadith.”

Another example is selling someone a commodity on deferred payment and then buying it back from him. In Sunan Abī Dāwūd, the Prophet, may Allah bless him and grant him peace, is reported to have said:

“Whoever concludes two sales in one may take the lower of the two prices, or else incur usury.”

Three-party transactions include bringing in an intermediary to make usury appear lawful. The usury-taker buys the commodity from this intermediary, then sells it on deferred payment to the usury-payer, who sells it back to its original owner at a price reduced by an amount that the intermediary gains.

Some of these transactions are forbidden by the consensus of the Muslims: for example, those in which such an arrangement is stipulated; those in which the commodity is sold before possession has been taken as required by Islamic law, or without fulfilling the conditions required by Islamic law; and those in which an insolvent debtor’s debt is rolled over at an increase. An insolvent debtor must be granted time to pay, and, by the consensus of the Muslims, it is impermissible to increase what he owes through a transaction or otherwise. Some scholars have disagreed over other forms of these transactions, but what is established from the Prophet, may Allah bless him and grant him peace, the Companions and the Successors is that all of them are forbidden.

Practices to be condemned also include intercepting goods before they reach the market. The Prophet, may Allah bless him and grant him peace, prohibited this because it involves misleading the seller: he does not know the market price, so the buyer purchases from him for less than the goods are worth. For this reason, the Prophet, may Allah bless him and grant him peace, granted the seller the right to rescind the sale once he reaches the market.

There is no doubt that he has this right when he has been underpaid. Whether he has it without having been underpaid, however, is disputed among the scholars. Two opinions are reported from Ahmad: the first recognizes this right, which is also the position of al-Shāfiʿī; the second does not