Deuteronomy 23:22-24

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; even a freewill offering, according as thou hast vowed unto Yhwh 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 any in thy vessel.