What is the ruling on one who swears by divorce that his manager is an ass, for example—may Allah honor you?

It is not permissible to describe a Muslim as a "donkey" (himar), because it is a forbidden insult. As for the ruling on swearing by "donkey," it is apparent that the intent was dullness (baladah) and not the animal itself. This oath has two possibilities: If he swore believing he was truthful, then there is nothing upon him, even if it later turns out to be otherwise. However, if he swore falsely, knowing it, then it is a "ghamus oath" (a false oath taken knowingly), and according to the majority of scholars, divorce occurs in such a case. Shaykh al-Islam Ibn Taymiyyah, however, holds that it does not occur if he intended it as an oath (i.e., not as a conditional divorce), and that anyone who did not intend divorce is not bound by it.