lives and property. Thus, they imposed liability upon the group as a whole, even when the individual responsible for the loss was unknown. If the amount plundered is unknown, so that neither what one side plundered from the other nor how much the other side plundered from them can be determined, the amounts are presumed equal. This is like someone whose wealth contains a mixture of lawful and unlawful assets, without his knowing which is greater: he relinquishes half his wealth, and the remaining half is lawful for him. Umar ibn al-Khattāb did this with the officials responsible for public funds: he divided their wealth in half, taking half the wealth of his officials in Syria, Egypt, and Iraq. He considered that some of the Muslims’ wealth had become mixed with theirs, but he did not know precisely which assets belonged to whom, or how much either side had taken from the other. Indeed, an individual might possess less than his entitlement or more. In such a case, each person is allowed to retain what is in his possession if he repents of cooperating in wrongdoing and aggression. For what cannot be ascertained is treated as nonexistent, and the obligation concerning it is waived. He must pay zakah on that wealth as its owner would.

If, however, he knows that his wealth includes both lawful assets that he owns and unlawful assets whose owners are unknown, and he knows the amount, he must divide the wealth in proportion to its lawful and unlawful portions. He takes the lawful portion, while giving the unlawful portion in charity on behalf of its owners. This is what someone does when he holds property whose owners are unknown, whether wrongfully seized property, borrowed items, or deposits entrusted for safekeeping. For the majority of scholars, such as Mālik