Numbers 30:2

30:2 If a man makes a vow to the Lord or takes an oath of binding obligation on himself, he must not break his word, but must do whatever he has promised.

Numbers 30:4

30:4 and her father hears of her vow or the obligation to which she has pledged herself, and her father remains silent about her, then all her vows will stand, and every obligation to which she has pledged herself will stand.