funds an amount equal to his claim is not to be judged to have taken something unlawful—especially if the holder has traded with the funds in his possession, for the claimant is then entitled to more than the amount of his original claim. There is, however, a risk that the funds in the holder’s possession may not suffice to meet the claims of everyone entitled to them. Yet those whose identities are unknown are treated as though they did not exist. Thus, if a person takes only what is due to him and does not wrong the other known creditors, we do not judge what he has taken to be unlawful. But if other creditors subsequently appear who are entitled to a share of the holder’s property, they may demand their rightful shares. Recovery is then made from each person who took possession of the property in proportion to the amount he took. And Allah knows best.

He also said—may Allah have mercy on him:

I was asked about people whose sheep or other property had been taken from them and then returned, in whole or in part, when one person’s property could no longer be distinguished from another’s.

I answered:

If the precise amount of each person’s property is known, whatever is available is divided among them in proportion to that amount. If only the number is known, it is divided in proportion to the number. This is because when two people’s property becomes mixed together, it is divided between them, even if each receives, in exchange for his own property, something that belonged to the other: the mixing has made them co-owners. This is particularly so according to our principle that a partnership may validly be established by contract even while the two parties’ assets remain distinct. The inability to distinguish ownership of sheep and similar property, however, has the same effect as the commingling of liquids.