described and owed, which is permissible provided the item, when delivered, conforms exactly to the description; whereas the sale of an absent item that has neither been seen nor described is impermissible. Every owned, pure object from which benefit can be derived may be sold, but it is invalid to sell an impure substance or anything that offers no utility.

Section. Usury applies to gold, silver, and foodstuffs. Thus it is not lawful to exchange gold for gold, or silver for silver, except in equal amounts with immediate, hand-to-hand payment. One may not resell what he has purchased until he has taken possession of it, nor may meat be exchanged for a live animal. Gold may be sold for silver with disparity, provided payment is immediate. Likewise, a food commodity may not be exchanged for the same commodity unless the amounts are identical and payment is on the spot, whereas exchanging one foodstuff for a different kind is permissible even with disparity, so long as the transaction is settled immediately. Sales involving excessive uncertainty (gharar) are prohibited.

Section. The two contracting parties retain the option of rescission (khiyār) so long as they have not separated, and they may stipulate an option period of up to three days. If the buyer discovers a defect in the goods, he may return them. It is not permissible to sell fruit outright before its ripeness has become apparent, nor to sell a commodity subject to usury for its own kind while still moist, with the sole exception of milk.

Section. A forward sale (salam) is valid—whether for immediate or deferred delivery—when five conditions are met: (1) the commodity is precisely defined by description; (2) it is of a type unmixed with anything else; (3) it has not undergone a transformative firing; (4) it is not a particular, identified item; and (5) it is not taken from a specified stock. For the salam contract itself to be sound, eight further conditions are required: after stating the genus and subtype, the seller must describe the commodity with the attributes that affect price; the quantity must be stated so as to remove ambiguity; if delivery is deferred, the due date must be specified; the item must normally be available at the time it falls due; the place of delivery must be identified; the price must be known; and that