Here, the person who swears an oath invoking divorce has committed himself to its taking effect by way of an oath, while disliking its occurrence if the condition is fulfilled—just as he dislikes falling into unbelief when he invokes it in an oath, and dislikes those acts of worship becoming obligatory upon him when he invokes them in an oath.
As for the objection, “He is swearing by other than Allah, so no expiation is binding upon him,” the reply is: The scriptural text concerns those who swear by created beings. This is why it describes such swearing as shirk (associating partners with Allah): the person has sworn by other than Allah. But someone who makes a sworn commitment to Allah binds himself more emphatically than someone who swears by Allah. This is why a vow is more emphatic than an oath. Thus, expiation is all the more obligatory for a commitment made to Allah than for an oath sworn by Allah. And Allah knows best.
He—may Allah Most High have mercy on him—was asked about the difference between divorce and swearing an oath, and to clarify the ruling on this.
He replied:
Praise be to Allah, Lord of all worlds. I bear witness that none has the right to be worshipped except Allah, and that Muhammad is His servant and Messenger. May Allah bless him, his family and his Companions, and grant them peace.
The expressions people use concerning divorce, manumission, vows, zihār, and declaring something forbidden to oneself fall into three categories.