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 observe and do; according as thou hast vowed unto Jehovah thy God, a freewill-offering, which thou hast promised with thy mouth.

24When thou comest into thy neighbor’s vineyard, then thou mayest eat of grapes thy fill at thine own pleasure; but thou shalt not put any in thy vessel.