Numbers 30:2

If a man vows a vow to the Lord , or swears an oath to bind himself by a pledge , he shall not break his word . He shall do according to all that proceeds out of his mouth .

When a man makes a vow to the Lord or takes an oath to obligate himself by a pledge, he must not break his word but must do everything he said.

If a man vow a vow unto the Lord, or swear 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.