Numbers 30:2
2 If a man vows a vow to the Lord, or swears an oath to bind himself by a pledge, lhe shall not break his word. He shall do according to all that proceeds out of his mouth.
Deuteronomy 23:21–23
21 c“If you make a dvow to the Lord your God, you shall not delay fulfilling it, for the Lord your God will surely require it of you, and you will be guilty of sin. 22 But if you refrain from vowing, you will not be guilty of sin. 23 You shall be careful to do what has passed your lips, for you have voluntarily vowed to the Lord your God what you have promised with your mouth.