; whoever cannot afford this must fast for three days. That is the expiation for your oaths when you have sworn them. And guard your oaths.”

These verses contain important principles, but explaining them requires some preliminary points that are extremely useful in this subject and others.

“The First Preliminary Point”

An oath comprises two clauses: a clause by which one swears and a clause stating what one swears to. Questions concerning oaths relate either to the ruling on what one swears by or to the ruling on what one swears to.

As for what one swears by, the oaths sworn by Muslims that may entail legal consequences fall into six categories, with no seventh:

First: an oath by Allah, and equivalent expressions involving a commitment to disbelief should the stated condition be fulfilled, such as saying, “I am a Jew or a Christian if I do such-and-such”—subject to the disagreement among the jurists concerning this.

Second: an oath by means of a vow, known as a “vow of obstinacy and anger,” such as saying, “The Hajj shall be binding upon me: I will not do such-and-such”; “If I do such-and-such, the Hajj shall be binding upon me”; or “My wealth shall be given in charity if I do such-and-such,” and similar expressions.

Third: an oath invoking divorce.

Fourth: an oath invoking the freeing of a slave.

Fifth: an oath invoking prohibition, such as saying, “Prohibition shall be binding upon me: I will not do such-and-such.”

Sixth: zihār, such as saying, “You are to me like my mother’s back if I do such-and-such.”

These comprise all the forms of oath sworn by Muslims that entail legal consequences.