Numbers 30:4 - Joseph Benson’s Commentary on the Old and New Testaments

And her father hear her vow Either when she spake the words, or by her acquainting him therewith, as she was bound to do. If it be asked why sons are not mentioned as well as daughters, since both, in their younger years, are under the power of their parents; the answer is, that the cases are quite different; for the sons may soon have it in their power, when become masters of families, to perform the vows which they had made in their minority; but daughters, who pass from the father's jurisdiction into the power of a husband, are perpetually dependant, either upon their fathers or husbands, and so have no right to make vows without the consent either of the one or the other, except in the case of widowhood or divorce, which is specified, Numbers 30:9.