Does the oath of ẓihār fall upon the wife if she leaves the apartment without her husband's permission, knowing that he told her: "I have nothing to do with anyone," and she thought that was permission to leave?

Contingent Zihar (a pronouncement by which a husband declares his wife to be unlawful to him, like his mother's back) takes effect when the condition it is contingent upon is met. However, some scholars, like Ibn Taymiyyah, are of the view that contingent Zihar, if not intended to bring about the Zihar itself but rather to prevent or encourage an action, takes the ruling of an oath, and thus requires an expiation for breaking an oath (kaffarat yamin (definition)).

If the wife performs the action upon which the Zihar was contingent, while she was acting on a misconception, or out of forgetfulness, or ignorance, then there is a difference of opinion regarding whether the Hinth (breach of the oath/vow) occurs. Ibn Taymiyyah holds that divorce does not occur in such cases.

Accordingly, nothing is binding upon you due to your wife's going out, as she misinterpreted your words as permission for her. We also draw attention to the fact that a permissible oath is sworn by Allah Almighty, and swearing by Zihar is a reprehensible falsehood.