The first of the two cases is when the subject-matter of the salam is food. Mālik based this ruling on his well-known position that the only commodity whose sale requires immediate possession is food, as the Prophetic report explicitly states.

The second is when the subject-matter is not food, yet at maturity the buyer takes in lieu of it something for which it would not have been lawful to advance the price in the first place. An example would be that the object of the salam is merchandise and the price is merchandise of another kind; when the term falls due the buyer takes from the seller an article belonging to the same kind as that price-merchandise. Such an arrangement entails either a loan plus an increment—if the article received is larger in quantity than the capital of the salam—or a guarantee together with a loan—if it is equal to, or less than, that capital.

Likewise, if the capital of the salam is food, it is impermissible for the buyer to take in exchange a greater amount of any other food, whether of the same genus or a different one. If, however, the replacement matches his food in genus, measure, and description—as ʿAbd al-Wahhāb relates—then Mālik allows it, treating it as merchandise (ʿurūḍ).

In the same vein, Mālik permits the buyer to take, in place of the stipulated food, another food of the same description even if it is of lower quality, regarding this as analogous to substituting different gold coins for dinars. A commendable act of generosity would be, for instance, that he is owed wheat and, in its measure, accepts barley instead. All of these concessions, however, are conditioned on immediate delivery, for otherwise the transaction would become a “debt for a debt.”

If the capital of the salam is hard currency and the buyer takes currency of the same species, the substitution is lawful so long as it is not greater than what he paid and no suspicion arises of an exchange of identical currencies on credit. The same holds if he takes dirhams in place of dinars—no charge of deferred currency exchange applies—or if he takes dinars of a type different from those that formed the capital of the salam.

As for selling the subject of a salam to someone other than the original seller, it is permissible for any commodity that may lawfully be sold, provided it is not food, because the prohibition of selling food before taking possession would otherwise apply.

With respect to revocation (iqāla), Mālik stipulates that no increase or decrease enter into it. Should an addition or reduction occur, the arrangement becomes an outright sale and is therefore subject to all the rulings governing credit sales—that is, it is invalidated by whatever invalidates deferred transactions, such as using it as a device to combine a sale with a loan, to employ the stratagem of “reduce the debt and expedite,” or to exchange the object of salam for something whose sale is unlawful.

An illustration of such a combination of sale and loan is the following: the term falls due, the parties agree to revoke the contract on the basis that the buyer takes part of the goods and is released from the rest. This, in Mālik’s view, is impermissible because it opens the door to a sale coupled with a loan. Al-Shāfiʿī and Abū Ḥanīfah, however, allow it, for they do not subscribe to the doctrine that forbids transactions serving as pretexts (buyūʿ al-dharaʾiʿ).

Issue
The scholars have differed about purchasing, with the capital of the salam, something from the seller after revocation that could not have been purchased before revocation. Some jurists do not permit this at all, viewing the revocation as a stratagem to legalize what is otherwise forbidden; this is the position of Abū Ḥanīfah and his associates, and of Mālik and his companions—except that, according to Abū Ḥanīfah, it is absolutely impermissible, since he prohibits selling the subject of a salam before possession under every circumstance, whereas Mālik