Deuteronomy 23:23-24

23:23 That which is gone out of thy lips thou shalt keep and perform; [even] a freewill offering, according as thou hast vowed unto the LORD thy God, which thou hast promised with thy mouth. 23:24 When thou comest into thy neighbour’s vineyard, then thou mayest eat grapes thy fill at thine own pleasure; but thou shalt not put [any] in thy vessel.