Deuteronomy 23:21
King James Version
“When thou shalt vow a vow unto the LORD thy God, thou shalt not slack to pay it: for the LORD thy God will surely require it of thee; and it would be sin in thee.”
Context
18Thou shalt not bring the hire of a whore, or the price of a dog, into the house of the LORD thy God for any vow: for even both these abomination unto the LORD thy God.
19Thou shalt not lend upon usury to thy brother; usury of money, usury of victuals, usury of any thing that is lent upon usury:
20Unto a stranger thou mayest lend upon usury; but unto thy brother thou shalt not lend upon usury: that the LORD thy God may bless thee in all that thou settest thine hand to in the land whither thou goest to possess it.
21When thou shalt vow a vow unto the LORD thy God, thou shalt not slack to pay it: for the LORD thy God will surely require it of thee; and it would be sin in thee.
22But if thou shalt forbear to vow, it shall be no sin in thee.
23That which is gone out of thy lips thou shalt keep and perform; a freewill offering, according as thou hast vowed unto the LORD thy God, which thou hast promised with thy mouth.
24When thou comest into thy neighbour’s vineyard, then thou mayest eat grapes thy fill at thine own pleasure; but thou shalt not put in thy vessel.