Numbers 30:1-3

1And Moses spake unto the heads of the tribes of the children of Israel, saying, This is the thing which the LORD hath commanded.

2When 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.

3Also when a woman voweth a vow unto the LORD, and bindeth herself by a bond, being in her father’s house, in her youth;