What is the ruling on a husband prohibiting his wife by saying, "You are forbidden to me if you go to your sister while intending anger and leaving the house," given that she went with the intention of anger and without informing him, and had intercourse with him upon her return without his knowledge of her intention?

A husband's statement to his wife, "You are forbidden to me," is an implicit expression (kinayah) that lacks the explicit intent (niyyah (definition)). If he intended zihar by it, then it is zihar, and he must pay its expiation. If he intended divorce by it, then divorce occurs. If he did not intend anything specific, but merely intended prohibition, then he must pay the expiation for an oath (kaffarat yamin (definition)). If he has intercourse with his wife before performing expiation, while ignorant of the condition being fulfilled, then there is no sin upon him. The sin is upon the wife who did not inform him of the reality of what she did.