for them, unless they are paid more than the customary price. In such a case, they must sell them at their fair market value. Price-setting means nothing more than requiring them to accept that value, so they must abide by what Allah has required of them.
An even stronger case is where people have agreed that only certain designated individuals may sell food or other goods: those goods are sold only to them, and they then resell them. If anyone else sells such goods, he is prevented from doing so—either unjustly, for the sake of a levy collected from the seller, or justifiably, because of the harm involved. Here, prices must be set for these dealers so that they neither sell goods nor buy people’s property except at fair market value. No scholar has any hesitation on this point. For if others have been prevented from selling or buying that type of goods, allowing these dealers to sell or buy at whatever prices they choose would wrong people in two ways: it would wrong those wishing to sell such goods, and it would wrong those buying from these dealers.
When not all injustice can be prevented, the duty is to prevent as much of it as possible. Price-setting in such circumstances is therefore obligatory, without dispute. In essence, it means requiring them to sell or buy only at a fair market price. This is obligatory in many situations under Islamic law.
Just as compelling someone to sell is impermissible without a rightful basis, it is permissible when there is a rightful basis, as when property is sold to discharge a debt that must be paid or to provide obligatory maintenance. Likewise, compelling someone to sell only at a fair market price is impermissible without a rightful basis, but is permissible in certain cases, such as that of someone in dire need of