Deuteronomy 23:21-23 - Keeping Vows

21 When you make a vow to the Lord your God, you shall not delay to pay it, for it would be sin in you, and the Lord your God will surely require it of you. 22 However, if you refrain from vowing, it would not be sin in you. 23 You shall be careful to perform what goes out from your lips, just as you have voluntarily vowed to the Lord your God, what you have promised.