What is the ruling on one who swears by other than Allah, such as saying: "By the right of this Mus'haf" or "By the right of the Qur'an"? Is he required to offer an expiation for breaking an oath, or does divorce occur if he breaks his word?

The permissible oath is by Allah or by an attribute of His, and it is not permissible to swear by anything else. The preponderant opinion is that swearing by the Mushaf (the physical copy of the Qur'an) or by the Qur'an is a binding oath that obligates the one who breaks it to a single expiation, because it is an attribute of Allah Almighty. The same ruling applies to whoever says: "By the right of the Mushaf" or "By the right of the Qur'an." So, for whoever says: "By the right of this Mushaf, if you do not go to so-and-so, I will expel you from the house," if the person sworn upon does not go and the swearer does not expel him, then the swearer breaks his oath and is obligated to an expiation for an oath. However, if he expels him, he does not break his oath. And for whoever says: "By the right of the Qur'an, if you do not do such-and-such, I will divorce my wife," if the person sworn upon does not do the intended action, his wife is not divorced by that. He has the choice between divorcing her, thus fulfilling his oath and no expiation is required of him, or keeping her, in which case he breaks his oath and is obligated to an expiation for an oath.