Deuteronomy 23:21-23

VIN(i) 21 "When you make a vow to the LORD your God, don't delay paying it, because the LORD your God will certainly demand payment from you, and then you will be guilty of sin. 22 But if you refrain from making a vow, then you won't be guilty. 23 Whatever your lips have said, see that you do it; for you gave your word freely to the Lord your God.