Does divorce occur if I swore by divorce that if my wife wrongs my mother, and then she wronged her?

"By Allah, if my wife wrongs my mother again, I will divorce her." This is a threat. If your wife wrongs [your mother], you would be faced with two choices: fulfilling the oath and divorcing her, or breaking the oath and not divorcing her, while being obligated to offer an expiation for breaking an oath (emancipating a slave, or feeding ten poor people, or clothing them; if you cannot find [any of these], then fasting for three days). This differs from conditioning divorce with the statement: "If my wife wrongs [my mother], she is divorced." One should be cautious about being careless with words of divorce.