Nadhr (vow)

A nadhr (vow) is, in juristic usage, a legally competent person's binding himself to God by word to something not already obligatory under the law. It differs from what is divinely imposed (fard) in that the vower imposes it on himself, and from voluntary devotion (tatawwu') in that it creates a commitment. ¹

There is no disagreement on the validity of the vow in principle and on the obligation of fulfilling what is an act of obedience — established by Book, Sunna and consensus: in the Book, the description of the righteous who "fulfil their vows"; in the Sunna, "whoever vows to obey God, let him obey Him, and whoever vows to disobey Him, let him not disobey Him", and Umar's pre-Islamic vow of a day's retreat in the Sacred Mosque, which the Prophet ﷺ told him to fulfil. ^{2 3}

Jurists differed over the legal character of vowing itself: one tendency treats it as recommended — with internal qualifications — and another as disliked, taking the outward sense of the hadiths that discourage it; both agree on the obligation of fulfilling a vow of obedience. ³