Is expiation obligatory upon one who said to his brother, "Your property is unlawful to me," then ate of his food and accepted his gifts and clothes, without taking any cash from him?

If a man forbids for himself something permissible, it is considered a vow, and expiation for breaking an oath (kaffarat yameen) becomes obligatory upon him if he breaks it, based on the Almighty's saying: (Allah has already ordained for you [Muslims] the dissolution of your oaths). The reference for oaths is the intention of the one swearing. If the wording allows for multiple meanings, the intention is what matters. If someone says to his brother: "Your money is forbidden to me," and he intended only cash, then there is no breaking of the oath if he takes food. But if he intended everything of value, then expiation for breaking an oath becomes obligatory upon him if he eats. If the intention is unclear, one should refer to the reason for the speech or common custom. If gifts and clothes were accepted, then the one who swore the oath owes expiation for breaking an oath. In summary: If he intended only cash, the oath is binding, and accepting non-cash items is permissible. If he intended everything of value, then the oath is dissolved, and expiation for breaking the oath is obligatory. If he sees good in dissolving the oath, then he should pay expiation for it.