What is the ruling on a wife who leaves her home without her husband's knowledge and permission, despite his warning her not to leave, and his telling her: "If you leave without my knowledge, then you are not my wife"?

It is not permissible for a wife to leave her husband's house without his permission. Doing so is considered an act of defiance (nushooz) and disobedience, unless her departure is due to an unavoidable necessity. The husband's statement to his wife, "If you leave after I am gone, you are not my wife," is considered an indirect divorce (kinayah talaq) conditioned on her departure. If he intended divorce by it, then it takes effect upon the fulfillment of the condition; otherwise, it does not. In the event of divorce, he may take her back (raj'ah) if it does not complete the three divorces and if it is before the end of her waiting period (iddah).