Rashi on Numbers 30:8/רש"י על במדבר ל׳:ח׳

1ושמע אישה וגו׳ BUT IF HER HUSBAND HEARD etc. — Here you have the case that if the husband confirmed the vow, it is confirmed. (That the father may confirm the vows of his betrothed daughter is given in v. 5 which statement applies also to w. 6 ff. — see Note).