Rules Regarding Oath (Qasam)
2679. If a person takes an oath that he will perform an act or will refrain from doing an act, for example, that he will fast or he will not smoke; if he does not intentionally act according to his oath, he should give Kaffarah for it, which means he should set a slave free, or he should feed ten indigent persons until they are satisfied, or should provide ten indigent persons with clothes. Moreover, if he is not able to perform these acts, he should fast for three consecutive days.
2680. The conditions for validity of an oath are:
1. A person who takes an oath should be Baligh and sane, and should do so with free will and clear intention. Hence, an oath by a minor, an insane person, an intoxicated person, or by a person who has been coerced to take an oath, will not be in order. Similarly, if he takes an oath involuntarily, or unintentionally, in a state of excitement, the oath will be void.
2. The act for which he took an oath should not be Haraam or Makrooh. Similarly, to renounce an act for which he took an oath should not be obligatory or Mustahab. In addition, if he takes an oath to perform a normal or usual act, it will be valid, if renouncing that act is not considered better than performing it in the estimation of sensible people. Similarly, if he takes an oath for renouncing a usually permissible act, it will be valid if the sensible people do not consider performing that act better than renouncing it.
3. A person must swear the oath by one of those names of the Almighty Allah, which are exclusively used for Him, for example, God, and Allah. Similarly, even if he swears by a name which is used for other beings also, but is used so extensively for Him, that when any person utters that name one is reminded of Allah alone, for example, if he swears by the name Khaliq (the Creator) and Raziq (the Bestower), the oath will be in order.
4. The oath should be uttered in words, and if someone writes it or make its intension in his mind, the oath is not in order. However, a dumb person can take an oath by making a sign.
5. It should be possible for him to act upon his oath. In addition, if he was able to act upon the oath when he took it, but became incapable of acting upon it later, the oath becomes nullified from the time he became incapable of acting upon it. If acting upon one’s oath involves unbearable hardship or the act is either superseded by another act or it becomes Haraam at the time of performing it, the oath is nullified. The same rule is for the vow and covenant.
2681. If the son takes an oath to perform an act and his father says to him that “do not perform it”, or if the son took the oath to renounce an act and his father says, “perform it”, the oath will become invalid.
2682. If a wife takes an oath without the permission of her husband to renounce an act and his husband says, “perform it” or if the wife took the oath to perform an act and the husband says, “do not perform it”, the oath of the wife will become invalid.
2683. If a person does not act upon his oath because of forgetfulness or helplessness, Kaffarah will not become obligatory upon him. In addition, the same rule applies, if he is forced to refrain from performing his oath. Moreover, if an obsessed person takes an oath like, if he says, "By Allah, I am going to offer prayers now at once" and then does not offer prayers owing to the whims haunting him, which renders him incapable of acting according to the oath it is not necessary for him to give Kaffarah.
2684. If a person swears to confirm that he is telling the truth, and if that is actually the truth, such swearing is Makrooh; and if it is a lie, swearing is Haraam and it is amongst the major sins. However, if a person takes a false oath in order to save himself, or another Muslim from the torture of an oppressor, there is no objection in it, in fact, at times it becomes obligatory. Nevertheless, if a person can resort to dissimulation (Tauriyat), that is, if at the time of taking an oath, he makes a vague, feigned utterance with no intention of resorting to falsehood, as per obligatory precaution, he should dissimulate. For example, if an oppressor or a tyrant, who wants to harm someone, asks him whether he has seen that person, and he had seen that person an hour ago, he would say that he has not seen that person, meaning in his mind that he has not seen him during the last few minutes.