the speech of every nation and every people. When they address one another concerning sales, leases, endowments, bequests, vows, or other matters, their words must be understood by reference to their intent, what their customary manner of expression indicates about that intent, and the accompanying circumstances.

As for treating the stipulations of an endowment founder, or those of any other contracting party, as equivalent to the Lawgiver’s texts in being obligatory to implement, this is disbelief by agreement of the Muslims. No human being other than the Messenger of Allah—peace and blessings be upon him—is to be obeyed in everything he commands. Conditions that accord with the Book of Allah are valid; those that contradict it are invalid.

As established in the two Sahīh collections, the Prophet—peace and blessings be upon him—delivered a sermon from his pulpit and said:

“What is the matter with people who stipulate conditions that are not in the Book of Allah? Whoever stipulates a condition that is not in the Book of Allah, it is invalid, even if there are a hundred conditions. The Book of Allah has greater right to be followed, and Allah’s condition is more binding.”

The imams agree that the ruling expressed in these words applies to sales, leases, endowments, and other transactions, whether or not the Lawgiver’s wording encompasses them. Either the general scope of the wording, rather than the particular occasion that prompted it, is what counts, or its application to conditions outside sales follows through analogical reasoning, on the basis of its general meaning.