Definition and the Lawful Object of an Oath
In Islamic law the oath (al-yamin, also called al-half or al-qasam) is a solemn affirmation by which a person confirms or strengthens a statement or commits to do or abstain from an act, invoking the name of God so that breaking it incurs both sin and a defined legal consequence. The Arabic word yamin originally denoted the right hand, which the pre-Islamic Arabs would join when concluding a covenant, and the term came to signify the binding power of the sworn word itself. The jurists agree that a genuine oath can be contracted only by swearing by God (Allah), by one of His revealed names such as al-Rahman, or by an attribute of His essence such as His might, His life, or His speech (the Quran). The Prophet declared, ‘Whoever swears, let him swear by God or remain silent,’ and forbade swearing by one’s father, by the Ka’ba, by trust (amana), or by anything created. The four Sunni schools and the Ja’fari school concur that swearing by a creature is prohibited; the Hanafis and others treat such an utterance as no true yamin at all, so that its violation entails no kaffara, while still regarding the act as blameworthy.
The Quran establishes the framework in two principal verses. Surah al-Baqara 2:225 teaches that ‘God will not call you to account for laghw in your oaths, but He will call you to account for what your hearts have earned,’ grounding the distinction between the heedless tongue and the resolved heart. Surah al-Ma’ida 5:89 then states that God does not hold one accountable for laghw but for ‘the oaths you have deliberately bound (ma ‘aqqadtum al-ayman),’ and proceeds to specify the expiation owed when such a bound oath is broken.
The Three Categories of Oath
Classical fiqh divides oaths into three kinds. The first is al-laghw, the idle or unintended oath: the habitual interjections of speech, ‘no, by God’ and ‘yes, by God,’ uttered without any settled intention to swear, or, in another well-known reading transmitted from A’isha, an oath about a matter the speaker sincerely believed true but which proved otherwise. For laghw there is neither sin nor kaffara, since 2:225 and 5:89 both exempt it. The second kind is al-yamin al-mun’aqida, the contracted or binding oath, in which a person knowingly and deliberately resolves to do or refrain from a future act, for example, ‘By God, I shall not speak to so-and-so.’ This is the oath that genuinely binds; should the swearer break it, or find that piety requires breaking it, expiation becomes due. The four Sunni schools and the Ja’fariyya broadly agree on these contours, differing in detail on what counts as a sincere intention and on whether certain conventional phrases bind.
The third kind is al-yamin al-ghamus, the false deliberate oath, sworn knowingly about a past or present matter that the swearer knows to be untrue, typically to seize another’s right or to deceive. It is called al-ghamus, ‘the plunging oath,’ because, as the hadith literature explains, it plunges its author into sin and ultimately into the Fire. The jurists rank it among the major sins (al-kaba’ir). Because its harm lies in deliberate falsehood and injustice rather than in a broken commitment, the majority of jurists hold that the ghamus is too grave to be lifted by the ordinary kaffara; what it requires is sincere repentance (tawba nasuh) before God and the restoration of any right wrongfully taken. The Shafi’is are noted for permitting kaffara for the ghamus as well, treating it as a binding oath that has been violated, but the dominant view across the schools confines expiation to the broken mun’aqida.
Expiation (Kaffarat al-Yamin) and Related Rulings
When a binding oath (mun’aqida) is broken, Surah al-Ma’ida 5:89 prescribes the kaffarat al-yamin: feeding ten needy persons with the average food one gives one’s own family, or clothing them, or freeing a believing slave; and whoever cannot find the means for any of these must fast three days. The choice among the first three options belongs to the one expiating, while the fast is a fallback for the one unable to perform them. Jurists discuss the measure of food, whether the clothing must suffice for valid prayer, and, in the Ja’fari and some Sunni discussions, whether the three days of fasting must be consecutive. A celebrated principle, rooted in the Prophet’s teaching, holds that ‘if one swears an oath and then sees that something else is better, let him do that which is better and make expiation for his oath’ — so that an oath binding one to a sinful or harmful course should be broken, the better act performed, and the kaffara paid, rather than the oath being kept.
Fiqh al-Yamin connects closely with the law of vows (nadhr), where a person binds himself to God by a pledge, and with the wider law of expiations (kaffarat) for breaches such as those of zihar and of the fast. It also borders the law of contracts and conditions, since oaths frequently reinforce undertakings, and the law of the lian, the sworn imprecation between spouses. In all these, Islamic jurisprudence preserves a careful balance: it honours the gravity of invoking the divine name, protects the heedless tongue from undue burden, and reserves its sternest judgement for the one who weaponises a false oath against the truth and the rights of others.
See also: Fiqh Al Nadhr, Fiqh Al Kaffarah, Fiqh Al Zihar, Fiqh Al Lian, Fiqh Al Aqd Wal Shurut