Numbers 30:1-3

1Then Moses spoke to the heads of the tribes concerning the children of Israel, saying, “This is the thing which the Lord has commanded:

2If a man makes a vow to the Lord, or swears an oath to bind himself by some agreement, he shall not break his word; he shall do according to all that proceeds out of his mouth.

3“Or if a woman makes a vow to the Lord, and binds herself by some agreement while in her father’s house in her youth,