Sifrei Bamidbar 156

(Bamidbar 30:14) "And if her husband be silent, silent to her from day to day": This is the silence of taunting. You say this, but perhaps it is the silence of confirmation (of the vow)? (This is not so, for Ibid. 12) "and he was silent to her" already speaks of the silence of confirmation. How, then, is "and he be silent, silent" to be understood? As referring to the silence of taunting. "from day to day": I might think, from time to time (i.e., for a twenty-four hour period); it is, therefore, written "which are upon her. He has confirmed them for he was silent to her on the day of his hearing" (i.e., until the night). R. Shimon b. Yochai says: "from time to time (i.e., a twenty-four hour period)," it being written "from day to day."

(Bamidbar 30:16) "And if he annul them after his hearing": after his confirmation of the vow. You say this, but perhaps it is "after his hearing," literally? (This cannot be, for) "for he was silent to her on the day of his hearing" already speaks of hearing. How, then, am I to understand "after his hearing"? As after his confirmation of the vow. "And if he annul them after his hearing," i.e., after his confirmation (and she breaks her vow), "then he shall bear her sin." (i.e., he takes her place for (punishment of) the sin. Now does this not follow a fortiori, viz. If in respect to G-d's measure of punishment, which (relative to that of reward) is small, one who causes his neighbor to go astray takes his place for punishment, then, in respect to His measure of good, which is (relatively) large, how much more so (is one rewarded for being instrumental in his neighbor's mitzvah)!

(Bamidbar 30:17) "These are the statutes which the L-rd commanded Moses, between a man and his wife, between a father and his daughter": Father is likened to husband, and husband to father in all of the ways we have mentioned "in her maidenhood (in) the house of her father", but not "in her maidenhood" in the house of her husband (i.e., her husband, unlike her father, does have prerogatives in her vows beyond her maidenhood.) R. Yishmael says "in her maidenhood in the house of her father": Scripture here speaks of a betrothed maiden, her father and her husband (jointly) annulling her vows.