Numbers 30:1-3

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

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.

If a woman also vow a vow unto the LORD, and bind herself by a bond, being in her father’s house in her youth;