Numbers 30:1-2

Young's Literal Translation

30 And Moses speaketh unto the heads of the tribes of the sons of Israel, saying, `This [is] the thing which Jehovah hath commanded:

² `When a man voweth a vow to Jehovah, or hath sworn an oath to bind a bond on his soul, he doth not pollute his word; according to all that is going out from his mouth he doth.