When does divorce occur if a man says, "If I do not kill so-and-so, then my wife is divorced," and he does not do it?

If the swearer specifies a time for his oath—whether verbally or by intention—he reneges (hanith) if that time elapses without fulfilling what he swore to. If he does not specify a time, he does not renege until the last possible moment, which is the death of the swearer or the death of the one he swore to kill. The Malikis hold that the intention not to act constitutes reneging. The majority of jurists agree that a contingent divorce takes effect upon the occurrence of the condition it is tied to, whether the husband intended divorce or his intention was to threaten, contrary to Ibn Taymiyyah, who believes it does not take effect if intended as a threat, prevention, or encouragement, and that a kaffarah for breaking an oath suffices instead. It must be noted that unlawful killing is one of the greatest sins.