Talmud - Nedarim 86b נדרים פ״ו ב׳

Rather, Rav Ashi said that this is the reason Shmuel ruled in accordance with the opinion of Rabbi Yoḥanan ben Nuri: Although a person cannot consecrate an entity that has not yet come into the world, konamot are different. They are stringent and take effect in all cases, as their prohibited status is considered akin to inherent sanctity. When one person prohibits another from deriving benefit from a particular item by means of a konam, the forbidden item is treated as if it has inherent sanctity. It cannot be redeemed and can never become permitted. Because of its severity, a woman can forbid her handiwork to her husband by means of a konam, even though she is obligated to hand over the fruits of her labor to him. And this is in accordance with the opinion of Rava.

As Rava said: Consecration of an item to the Temple, becoming subject to the prohibition of leavened bread on Passover, and the emancipation of a slave abrogate any lien that exists upon them. The lien on that property does not prevent the consecration, the prohibition of leavened bread, or the emancipation of the slave from taking effect. In all three cases, the debtor loses his ownership of the liened property. The same halakha applies to a konam, whose prohibition has the severity of inherent sanctity. Even though the husband has a right to his wife’s handiwork, which could be described as a lien on her hands, that lien is abrogated when she renders her handiwork forbidden to him by means of a konam, and therefore the vow must be nullified.

The Gemara asks: If so, why do I need Rabbi Yoḥanan ben Nuri’s stated reason: Perhaps he will one day divorce her? If the woman’s konam abrogates the husband’s lien, the prohibition should take effect immediately. The Gemara answers: Teach that the vow takes effect right away, which is why the husband must nullify it. And furthermore, adds Rabbi Yoḥanan ben Nuri, even if you maintain that the Sages strengthened a husband’s lien so that the vow does not take effect immediately, there is another reason to nullify the vow, as perhaps he will one day divorce her.

MISHNA: If a man’s wife took a vow and he thought that it was his daughter who had taken a vow, or if his daughter took a vow and he thought that it was his wife who had taken a vow, or if his wife vowed to be a nazirite and he thought that she had vowed to bring an offering, or if she vowed to bring an offering and he thought that she had vowed to be a nazirite, or if she took a vow that figs are forbidden to her and he thought that she had taken a vow that grapes are forbidden to her, or if she took a vow that grapes are forbidden to her and he thought that she had taken a vow that figs are forbidden to her, and he nullified any of these vows, in each case, when he realizes his error with regard to the vow, he must repeat the action and nullify the vow a second time.

GEMARA: With regard to the mishna’s ruling that if a man’s wife took a vow, but he thought that it was his daughter who had taken the vow and he nullified the vow, he must nullify the vow a second time, the Gemara asks: Is this to say that the phrase “But if her husband disallowed her [otah]” (Numbers 30:9) is precise? In other words, does the use of the word her, otah, indicate that a man can nullify a vow only for the specific woman who took it?

Traduction : The William Davidson digital edition of the Koren Noé Talmud, with commentary by Rabbi Adin Even-Israel Steinsaltz.

Nedarim 86b explores why konam vows override a husband's claim to his wife's earnings, comparing this severity to consecrated property and freeing slaves.