Commentary for Numbers 30:9

והפר את נדרה AND HE (THE HUSBAND) ANNULS HER VOW — One might think that since confirmation by the husband does not require the assent of the father, in the case mentioned here it is annulled even if the father has not annulled it! It, however, states, (v. 17): "[These are the laws … relating to a father with his daughter] בנעריה בית אביה" which means: so long as she is בנעריה (not fully married) she is under her father’s control (Sifrei Bamidbar 155; Ketuvot 46b).

ואם ביום שמוע אישה אותה ...וה' יסלח לה, “and if on the day her husband hears about it ..he revokes it, etc.” the verse speaks about a situation when the father of the girl has already made use of his right to annul her vow. Under such circumstances her husband has the right to complete the annulment commenced in part by her father. This is why the Torah first wrote the additional words בנעוריה בית אביה, “while she was not of age and in her father’s house.” If the (wife) in question had made vows (in her father’s house while he was alive) prior to her becoming betrothed to her husband, her husband cannot revoke them. This is the meaning of Nedarim 72 that the husband cannot revoke vows made by his wife before she became betrothed to him, seeing that the principle that she automatically presumes her husband’s consent to such a vow would not have applied while she did not even know who her husband was going to be.
This assumption that vows are made on the understanding that both father and husband do not object is the only reason why a vow, i.e. an undertaking of Biblical force can be revoked by a husband invoking only rabbinical force. The example we have in mind is a twelve-year old who is fatherless but mature enough to understand the meaning of her vows who has been given in marriage to her husband by her mother.
The situation of a widowed woman we mentioned as category 4 above refers only to a woman who became a widow after having been fully married (חופה), i.e. after having lived with her husband. Her status, as well as that of a divorcee, is that she had no longer been under the authority of her father at all. Seeing that the authority of her father had ceased completely after she had received חופה, the final stage of becoming married, her father will not again have any authority over her regardless of her age. This also proves that the institution of חופה is Biblical in its legal force, and that once there had been חופה, if her husband is a priest he must defile himself at her burial, is entitled to inherit her, and is exclusively entitled to revoke her vows [inasmuch as they affect him. Ed.]

Perhaps even if the father did not annul… (Nachalas Yaakov) There is no doubt that [the title of this comment, as it appeared in the text of the Sifsei Chachamim] is a copyist’s error, for that verse (v. 13) refers back to “If she took the vow in her husband’s home” (v. 11) and the case where she was married. However, the text of Re’m is correct, for [its heading] reads, “He then annuls her vow.”