Does it constitute an irrevocable divorce if the husband tells his menstruating wife: "If you don't leave the house within a week, then you are divorced," given that he had previously divorced her twice?

Divorce pronounced over the phone takes effect if the husband intended it. If he did not intend it, the divorce does not take effect, and the wife remains under his marital bond.

If the husband intended divorce by message, and the condition upon which it was contingent—namely, not leaving the house before one week from the message's sending—is met, then the divorce takes effect according to the majority of scholars, and this is the preponderant opinion.

If the husband had divorced her twice before, then she becomes unlawful for him and is not permissible for him until she marries another man in a valid marriage and he consummates it with her, and then divorces her.

Shaykh al-Islam Ibn Taymiyyah and those who agreed with him held the view that divorce does not take place during menstruation. So, if the oath is broken during menstruation, the wife remains under his marital bond. However, if the divorce occurs while she is ritually pure, then it takes effect even according to Ibn Taymiyyah.