Swearing that his wife will be unlawful for him if she did something and she did it
If a man tells his wife that if she does such and such, she will be unlawful for him, then she does it;
does she become unlawful for him or not? Is it permissible for him to take her back in marriage in case she is considered divorced?
if his intention is to prevent her from doing a certain act then she does it, his statement is considered an oath and Kaffarah (expiation) for an oath must be offered. The Kaffarah is to feed ten Miskins (needy persons), or to provide them with clothing, or to emancipate a believing slave. If he cannot afford any of these, he must observe Sawm (Fast) for three days.
if he means by his statement to render his wife unlawful for him by likening her to one of his Mahrams (unmarriageable relatives), such as his mother or sister, it is considered Zhihar; and its Kaffarah is to emancipate a believing slave. If he cannot find any, he must observe Sawm for two consecutive months. If he is not able to observe Sawm, he must feed sixty Miskins before resuming intimacy with his wife. (Part No. 20; Page No. 298) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.