Is a wife forbidden to her husband if he returns to drug use after having sworn on the Book of Allah not to return, with the intention that she would be forbidden to him if he returned? What is the expiation for his oath? And is this method of swearing permissible?

A man's statement to his wife, "You are forbidden to me," depends on his intention. If he intended divorce, then it is a divorce. If he intended ẓihār (a pre-Islamic form of divorce by likening one's wife to a forbidden female relative), then it is ẓihār. If he did not intend anything, then it is an oath requiring expiation.

The wife's intention in determining the nature of the prohibition is not considered. If the husband intends divorce, the wife has no right to say she intends ẓihār. If the husband intends an oath to prevent something, the wife has no right to say she intends separation.

If the wife is certain that a divorce has occurred due to her husband's oath, she must act upon her certainty. If the husband denies it, she must account for it in the number of divorces. If it was the first or second divorce, he may take her back. If it was the third, she is irrevocably separated from him, and it is not permissible for her to allow him access to her.

An oath is based on the intention of the one who administers it.