If a man makes a vow to the LORD or swears an oath to obligate himself by a pledge, he must not break his word; he must do everything he has promised.
Jewish Publication Society of America Version (JPS1917) - Numbers 30:2 >(30-3) When a man voweth a vow unto the LORD, or sweareth an oath to bind his soul with a bond, he shall not break his word; he shall do according to all that proceedeth out of his mouth.