“When you vow a vow to Yahweh your God, you shall not be slack to pay it, for Yahweh your God will surely require it of you; and it would be sin in you.”
Deuteronomy 23:21 (WEB)
Context Reading
19You shall not lend on interest to your brother: interest of money, interest of food, interest of anything that is lent on interest. 20You may charge a foreigner interest; but you shall not charge your brother interest, that Yahweh your God may bless you in all that you put your hand to, in the land where you go in to possess it. 21When you vow a vow to Yahweh your God, you shall not be slack to pay it, for Yahweh your God will surely require it of you; and it would be sin in you. 22But if you refrain from making a vow, it shall be no sin in you. 23You shall observe and do that which has gone out of your lips. Whatever you have vowed to Yahweh your God as a free will offering, which you have promised with your mouth, you must do.