The Quran about vow
In the name of God, the Gracious, the Merciful.
Sincerity in the faith stimulates many believers to make a vow to God in fulfilment of this or that action. The motive of this action is usually dedicated to God, which, for example, may concern the ritual side. The vow in the Quran is denoted by the term “nuzuurun, nazrun.”
Then let them decide to calm down and fulfil their vows (nuzuurahum). Let them circle around the ancient house.” (22:29)
The vow imposes a special responsibility on the believer, because this action does not elude from the attention of the Almighty:
And whatever you spend of expenditures or make of vows (nazartum) – indeed, God knows of it. And for the obscurantists there are no helpers. (2:270)
Giving an account to an enormous responsibility in terms of execution of the vow, true believers in all circumstances strive to fulfil it:
They fulfilled vows (binnazri) and were afraid of a day whose evil is inevitable. (76:7)