Vow (Nazr)

Nazr, that is, adaq (vow), is a kind of worship. Nazr is performed only for Allahu ta'ala. It is not performed for men. There are two kinds of vowing: absolute nazr, and conditional nazr.

1 - Absolute nazr is, for example, to say, "I shall fast for one year for the sake of Allahu ta'ala." It is not dependent upon a condition. It becomes wajib [1] to fulfil it, even if one did not mean it while saying it or it slipped out inadvertently during a conversation. For, in matters of talaq (divorce) and nazr, uttering without an intention or thought is like uttering seriously and intentionally. In fact, if one inadvertently says, " fast for a month..," instead of saying, "Let it be a debt upon me to fast for a day for Allahu ta'ala," it becomes necessary for one to fast for a month.

2 - Conditional vow. When the condition one has desired occurs one has to fulfil the nazr. If one has made the nazr depend upon the occurrence of a condition one desires, one will have to fulfil the nazr when the condition one has stipulated occurs. If one has stipulated a condition one does not desire to occur, when the condition one does not desire occurs one fulfils the nazr if one likes, if the nazr is hajj [2] , fasting, alms, or supererogatory salat. If one does not want to fulfil the nazr of this kind, one may pay the kaffarat [3] for an oath instead. For example, if one says, "May it be my nazr to give a hundred pounds as alms for Allah's sake if I ever speak to Ali again," and then speaks to Ali, he has a choice between giving the alms or paying the kaffarat prescribed for an oath.

[1] wajib: (act, thing) never omitted by the Prophet, so almost as compulsory as fard and not to be omitted. Wajib al-wujud: Being whose existence is indispensable and nonexistence is impossible.
[2] hajj: fard pilgrimage to Mecca.
[3] kaffara: specified penalty that should be paid along with qada'.