required for their validity, examples include selling at the time of the Friday prayer, a townsman selling on behalf of a desert dweller, a man making a competing offer against his brother’s sale, sales made by intercepting incoming traders, sales separating enslaved family members, and similar transactions. Scholars hold two views concerning such sales when they occur. Those who consider that a prohibition does not entail the invalidity of the prohibited transaction do not rescind them, even when the goods remain available for restitution. Those who consider that a prohibition entails invalidity rescind them whether or not the goods remain available. If the goods remain available, the goods themselves are returned; otherwise, their value is returned, restitution of their value taking the place of restitution of the goods themselves. There is a third view concerning this category of sales: they are rescinded while the goods remain available, but otherwise stand at the agreed price, without recourse to their assessed value. This is an intermediate position between the two views, but it does not follow the dictates of legal analogy.
Section
The third category comprises sales that breach a condition of their validity. These must be rescinded in all cases, and neither party has any choice in the matter. The goods are returned to the seller if they remain available; otherwise, their value on the day possession was taken is returned. The seller returns the price to the buyer. Some of the conditions required for a valid sale have already been mentioned, including that the total price and the quantity of the goods be known. It is unnecessary to add “at the time of the contract” to this condition except according to the position of ‘Abd al-‘Azīz ibn Abī Salama, who does not permit purchasing a heap of grain by measure at one dirham per qafīz. This is because the total price and quantity of the goods are not known at the time of the contract, but become known only after measuring. Thus, if a man sells goods for an unknown price, or with payment deferred to an unknown date, or makes a similar transaction, the sale must be rescinded in all cases, whether or not the goods remain available, and whether the parties agree or refuse.
Section
The fourth category comprises sales with stipulations, which scholars call buyū‘ al-thunyā. Examples include a man selling an item on condition that the buyer neither sell it nor give it away; or selling a slave woman on condition that the buyer make her the mother of his child, that he not take her out of town, that he not practise withdrawal during intercourse with her, or that he not take her across the sea; or stipulating that, if the buyer sells her, the original seller have the first right to purchase her at the sale price; or that the seller retain an option to rescind until a date too distant for such an option to be permissible; or other similar stipulations that