Allah has permitted, for his condition would then invalidate Allah’s ruling. Likewise, he has no right to waive what Allah has made obligatory. Rather, a person may stipulate a condition that makes binding what would not otherwise be obligatory. The purpose of conditions is to make obligatory what was neither obligatory nor forbidden. The absence of an obligation does not preclude imposing one, such that the person stipulating it would be contradicting the revealed law.

Every valid condition must establish an obligation that did not previously exist. In a sale, each party becomes obliged to deliver to the other what he was not previously obliged to deliver. Likewise, things become permissible for each that were not previously permissible, and things become forbidden to each that were not previously forbidden. The same applies to the parties to contracts of hire and marriage. Likewise, if someone stipulates a particular quality in the item sold or requires a pledge as security, or a woman stipulates a dower exceeding that customary for women of her standing, the condition makes things obligatory, forbidden, or permissible that were not so before.

This is what misled those who believed that conditions are invalid by default. They argued:

“They must either permit something forbidden, forbid something permissible, make binding what is not due, or waive an obligation. None of this is permissible without the Lawgiver’s permission.”

This difficulty occurred to some people, leading them to imagine that this hadith was self-contradictory. That is not the case. Rather, whatever is forbidden without the condition cannot be made permissible by it, such as usury, intercourse with another person’s slave woman, or assigning the patronage arising from emancipation to someone other than the emancipator. Allah has forbidden intercourse except by virtue of marriage or slave ownership. Thus, if a man wished to lend his slave woman to another for intercourse, he would not be permitted to do so, unlike lending her for service, which is permissible. The same applies to patronage: