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;

Jamieson-Fausset-Brown Bible Commentary

3. 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-Girls only are specified; but minors of the other sex, who resided under the parental roof, were included, according to Jewish writers, who also consider the name "father" as comprehending all guardians of youth. We are also told that the age at which young people were deemed capable of vowing was thirteen for boys and twelve for girls. The judgment of a father or guardian on the vow of any under his charge might be given either by an expressed approval or by silence, which was to be construed as approval. But in the case of a husband who, after silence from day to day, should ultimately disapprove or hinder his wife's vow, the sin of non-performance was to be imputed to him and not to her [Nu 30:15].

Matthew Henry's Concise Commentary

30:3-16 Two cases of vows are determined. The case of a daughter in her father's house. When her vow comes to his knowledge, it is in his power either to confirm it or do it away. The law is plain in the case of a wife. If her husband allows her vow, though only by silence, it stands. If he disallows it, her obligation to her husband takes place of it; for to him she ought to be in subjection, as unto the Lord. The Divine law consults the good order of families. It is fit that every man should bear rule in his own house, and have his wife and children in subjection; rather than that this great rule should be broken, or any encouragement be given to inferior relations to break those bonds asunder, God releases the obligation even of a solemn vow. So much does religion secure the welfare of all societies; and in it the families of the earth have a blessing.