Nor is a bequest valid when it is directed toward sin—for example, a bequest to churches or to the temples of unbelievers and polytheists, or a bequest for erecting or lighting tomb-shrines, or for paying their custodians—whether the testator is Muslim or non-Muslim.

Shaykh al-Islām Ibn Taymiyyah said, “If a dhimmī were to set aside some of his own wealth as an endowment for their temples, it would not be permissible for Muslims to judge that endowment sound, for they may only rule according to what Allah has revealed. Among what Allah has revealed is the command not to cooperate in disbelief, wickedness, or disobedience—so how could they assist, by means of an endowment, the very places where disbelief is practiced?!”

Likewise, a bequest is invalid if it is meant to finance the printing of abrogated scriptures such as the Torah or the Gospel, or the printing of deviant works such as books of heresy or atheism.

Among the rulings on bequests is that what is bequeathed must be property or a lawful benefit, even if it is something that cannot presently be delivered—such as a bird in flight, a fetus in the womb, or milk still in the udder—or even something nonexistent, as when a person bequeaths whatever produce his animal or tree will yield, either indefinitely or for a set period like one year. If any of that nonexistent subject matter does come into being, it belongs to the beneficiary; if nothing comes into being, the bequest is void because it never attached to an actual object.

A bequest for something unspecified is valid. Thus, if he bequeaths “a slave” or “a sheep,” the beneficiary receives whatever item the term truly or customarily denotes.

Another ruling: if a person bequeaths one-third of his estate and then acquires additional wealth after making the bequest, the new property is included in that one-third, for the one-third is calculated at death on the wealth that exists at that time.