How can one verify the truthfulness of a wife who has habitually lied, especially after her husband told her: "If you lie, then you are divorced, and Allah is a witness to that"?

If a husband makes his wife's divorce contingent upon her lying about a matter he asked her about, then what is taken into consideration is the reality of the situation, if it can be ascertained. Otherwise, her word is to be considered. If the wife admits to her lie, the divorce takes effect according to the majority of scholars, contrary to Ibn Taymiyyah, who holds that an expiation for an oath is required if he did not intend divorce. If she states her truthfulness, the divorce does not take effect, even if she was actually lying, due to the lack of certainty that the condition has been met. The Malikis are of the view that the husband should separate from her in this case, but he is not compelled to do so. The husband should avoid swearing by divorce in the future.