«النذر نذران فما كان من نذر في طاعة الله فذلك لله وفيه الوفاء وما كان من نذر في معصية الله فذلك للشيطان ولا وفاء فيه ويكفره ما يكفر اليمين»
The Prophet (peace and blessings be upon him) said:
"Vows are of two kinds: a vow made in obedience to Allah is for Allah, and it must be fulfilled; and a vow made in disobedience to Allah is for Satan, and it should not be fulfilled, and its expiation is the same as the expiation for an oath."
Hadith Referenceصحیح الجامع الصغیر / حرف النون / 6804