Chapter: The Messenger of Allah ﷺ forbade ʿusb al-faḥl (the stallion’s stud service). ʿUsub means allowing the stallion to cover; others say it denotes its semen; still others say it is the fee taken for the covering. Accordingly, taking payment for the stallion’s semen is unlawful, and—according to the sounder opinion—the same applies to charging a stud fee.

He ﷺ likewise prohibited ḥabl al-ḥabla (the unborn of the unborn): that is, selling the future offspring of a future offspring, or selling something for a price deferred until that second-generation offspring is born.

He also forbade selling the mulāqīḥ (what is in the wombs) and the muḍāmin (what is in the loins of the males).

He prohibited mulāmasa (touch-sale), where one merely touches a folded garment and then buys it on condition that he will have no option after seeing it, or he says, “The moment I touch it I have bought it from you.”

He prohibited munābadha (throw-sale), in which the parties make the act of throwing an object constitute the sale.

He prohibited bayʿ al-ḥaṣāt (pebble-sale), such as when someone says, “I sell you whichever of these garments the pebble lands on,” or they treat the throw of a pebble as the act of sale, or he says, “I sell it to you and you may choose until the pebble is thrown.”

He forbade “two sales in one sale,” for example when a seller says, “I sell it to you for 1,000 in cash, or for 2,000 payable in a year,” or, “I sell you this slave for 1,000 provided you sell me your house for such-and-such.”

He forbade a sale coupled with a condition, such as making the sale contingent upon another sale or upon a loan. Thus, if someone bought standing crops on the condition that the seller harvest them, or bought cloth on the condition that the seller sew it, the preponderant view is that the contract is void.

Excluded from this ruling are cases such as a sale with an option period (khiyār), a clause disclaiming defects, a stipulation to pick the fruit, to defer payment, to provide collateral, to secure a guarantor, to fix the price as a debt, or to summon witnesses. According to the sounder view, naming the particular witnesses is not required. If the purchaser fails to provide the pledged collateral or the named guarantor, the seller may rescind.

If a person sells a slave on condition that the buyer emancipate him, the prevalent view is that both the sale and the condition are valid, and the sounder opinion further allows the seller to compel the buyer to carry out the manumission. However, if the seller, in addition to emancipation, stipulates that the slave’s walāʾ (clientage) revert to him, or that the slave be made mudabbar (promised freedom at the owner’s death), be placed under a kitāba contract, or be freed after a month, the sale is invalid.

If the condition merely restates what the contract already entails, such as taking possession or returning the item when a defect appears, or it concerns something of no real benefit—like stipulating that the buyer will eat only a certain food—the sale remains valid. Likewise, if the condition relates to a desirable attribute—such as that the slave be literate, or that the riding animal be pregnant or producing milk—the stipulation is valid.