His statement, “the waterwheel and the like”: the waterwheel is a device used to draw water from a well and the like. A millwheel may be used in place of a waterwheel: waterwheels are used with wells, whereas millwheels are used on rivers. We previously encountered the use of the millwheel in the chapter on the option arising from deception, where the author said, “Collecting water for the millwheel and releasing it when it is offered for sale.” This resembles the deception involved in retaining milk in the udder of a grazing animal.

Accordingly, in a musaqah arrangement, the waterwheel itself is the responsibility of the owner of the property, whereas turning it and setting it in motion—that is, operating it—is the worker’s responsibility.

His statement, “and the like,” means anything else required for the maintenance of the property.

If someone were to ask, “Where in the Book of Allah or the Sunnah of the Messenger of Allah, may Allah’s peace and blessings be upon him, is it stated that this is one party’s responsibility and that is the other’s responsibility?”

We reply: the matter is referred back to customary practice, in accordance with the well-known rule:

Whatever the Sacred Law has left undefined—
as with a place of safekeeping—by custom is determined. (1)

If the custom is consistent, then all is well; that is what is required, and we follow the prevailing custom. But if it is not consistent, each party must explain to the other what obligations and rights he has, so that no dispute arises. It is well known that, when the contracting parties first enter into an agreement, each is cautious, and one of them may forget—or pretend to forget—some of the conditions, saying, “This is insignificant.” But we say: this is not permissible. The matter must be clear and explicit, for a dispute may arise later, and then we may be unable to reconcile the two parties.