I used to give this fatwa in reliance on the opinions of others and on their argument that this is a ruling made contingent upon a condition, as when a man says, “If you do this, you are forbidden to me,” as a punishment for her for doing it. Later, however, I ruled that he owes expiation for an oath if his intention is to refrain from the act, not to bring about the prohibition. This accords with what we have said concerning a “vow prompted by obstinacy and anger,” and concerning a man’s declaration that he is a Jew or a Christian if he does such-and-such, or that he deems wine and carrion lawful if he does such-and-such.

For just as his intention in those cases is not for the stipulated consequence to take effect when the condition is fulfilled, but merely to refrain from an act, so too when he says that what is lawful is forbidden to him if he does such-and-such. His purpose is not to make lawful things forbidden upon performing the act, but to refrain from it. He mentions hypothetically undertaking that consequence to reinforce his resolve to abstain, just as he hypothetically undertakes to become a Jew or a Christian. Similarly, an oath sworn by Allah carries the meaning: “If I do this, I will have violated the sanctity of oaths sworn by Allah,” or, “I will have diminished the reverence due to Allah,” or, “I will have treated the sanctity of Allah lightly if I do it.”

What all oaths entail, according to their wording, is fulfillment; and whenever someone breaks his oath, he has violated his oaths and has become a Jew or a Christian. Likewise, the wording of a vow prompted by obstinacy and anger entails the obligation to fulfill it, for a ruling made contingent upon a condition becomes binding when that condition is fulfilled. Someone who swears by something to perform an act has committed himself to that act and bound it to the object of reverence by which he swears. Whenever he fails to perform it, he has violated that sanctity.