Does divorce take place if the wife says to her husband, "Leave me," during a phone call, after he threatened to divorce her if she said it?

One must be cautious about jesting in matters of divorce, because uttering it, whether seriously or in jest, carries the same weight. This is based on the Prophet's (peace be upon him) saying: "There are three matters, whose seriousness is serious, and whose jesting is serious: marriage, divorce, and revocation [of divorce]." And the phrase "I will divorce you if you tell me to leave me" does not constitute a divorce, because it is a promise of divorce.