Gemara

(Mishnah): If a woman forbade her earnings to her husband, he need not annul (the vow is void anyway);

R. Yochanan ben Nuri says, he should annul it, lest he divorce her, and the vow would prevent him from remarrying her.

(Gemara - Shmuel): The Halachah follows R. Yochanan ben Nuri.

Inference: Shmuel holds that a man can make Hekdesh (which has the same law as forbidding through a vow) something that is not yet in the world.

Contradiction: Shmuel ruled that if one was Makdish his wife's earnings, he cannot be Makdish Davar she'Lo Ba l'Olam (something not yet in the world)!

Answer (Rav Huna brei d'Rav Yehoshua): The case is, she said 'my hands are Hekdesh to their Maker.' Her hands are in the world.

Question: Her hands do not become Hekdesh. They are Meshubad to (obligated to work for) her husband!

Answer: She said 'when I will be divorced.'

Question: Right now, she is not divorced! Do we ever find that something does not become Hekdesh now, and it becomes Hekdesh later?

Answer (Rav Ashi): Konamos are like Kedushas ha'Guf (something used for Avodas ha'Mikdash), like Rava taught:

(Rava): Hekdesh, the Isur of Chametz, and freeing a slave uproot liens.

Question: If so, her earnings should become forbidden immediately. Why does the Mishnah say that the concern is lest he divorce her?

Answer: It teaches another reason. (The text of many Meforshim, and the Gemara in Kesuvos 59b, answers that Chachamim strengthened his lien.)

47a (Rami bar Chama) Question: If one said 'this produce is forbidden to Ploni', may Ploni benefit from Chilufeihem (what it is exchanged for)?

Since one cannot forbid his friend's property to his friend, he cannot forbid to his friend Davar she'Lo Ba l'Olam. Or, perhaps Chilufeihem is forbidden, just like what grows from them!

(Rava): Perhaps it is forbidden only l'Chatchilah to exchange what is forbidden, but b'Di'eved, it is permitted!

Rishonim

Rif and Rosh (11:1): If a woman forbade her earnings to her husband, he should annul it, lest he divorce her, and the vow would prevent him from remarrying her. One cannot be Makdish Davar she'Lo Ba l'Olam. The case is, she was Makdish her hands. Even though her hands are Meshubad to her husband, Konamos are like Kedushas ha'Guf, which uproots liens. Her earnings are not forbidden immediately because Chachamim strengthened the lien of a husband.

Rambam (Hilchos Nedarim 12:10): If a woman said 'my hands are Hekdesh to Hashem', or vowed that her husband not benefit from her earnings, it is void, because her hands are Meshubad to him. Even though Hekdesh uproots liens, his lien is only forbidden, so Chachamim strengthened it and she cannot uproot it. He should annul her vow, lest he divorce her and be unable to remarry her.

Rebuttal (Ran Kesuvos 24a DH u'Parchinan): Why does the Rambam say that a vow that her husband not benefit from her earnings takes effect after divorce? It is Davar she'Lo Ba l'Olam, unless she is Makdish her hands!

Defense (Kesef Mishneh): Perhaps the last words of the Rambam (he should annul, lest he divorce her...) apply only to when she was Makdish her hands. It is better to say that these words apply in both cases. The Rambam holds that we conclude that Konamos uproot liens, because they are Kedushas ha'Guf, i.e. one cannot redeem the Isur. Therefore, even when she forbids earnings, it takes effect for after divorce. We say that one cannot be Makdish Davar she'Lo Ba l'Olam only regarding Kedushas Damim.

Rebuttal (Nekudas ha'Kesef YD 234:4): The Gemara said only that Konamos are different like Rava taught, because they uproot Shibud. Rava himself (47a) agreed that one cannot forbid Davar she'Lo Ba l'Olam to someone else.

Gra (YD 234:129): Kidushin 63a asked how one can forbid his wife's earnings. It answered (only) that he was Makdish her hands for their deeds. However, Tosfos (DH v'Yadayim) says that it could also have answered that Konamos forbid even Davar she'Lo Ba l'Olam. However, it is not clear why the Rambam forbids (after divorce) even when she was Makdish her hands without Konam. Her hands are Meshubad to her husband!

Ran (DH mid'Omrinan): Even though Rav Huna holds that one can tell her husband 'don't feed me, and I will keep my earnings', she cannot be Makdish her hands because some tasks, e.g. grinding, baking and cooking, she must do in any case. She cannot 'redeem' herself. R. Yochanan ben Nuri says that he would not be able to remarry her, for after divorce even these are forbidden. One can be careful not to benefit from his wife's earnings, but she cannot be careful not to cook or mix a drink for him.

Tosfos (Kesuvos 59a DH Shma): We are not concerned lest she say 'don't feed me, and I will keep my earnings', for this is not common.

Hagahos Ashri (Kesuvos 5:16): If he is not feeding her, her vow takes effect immediately if she made her hands Hekdesh. If she was Makdish what she will produce, this is Davar she'Lo Ba l'Olam. One can forbid Davar she'Lo Ba l'Olam to himself through Konam, but not to another

Ran (ibid.): Rashi says that Konamos, which forbid just to one person, are not like true Hekdesh, which has Pidyon (redemption). There is no Pidyon for Konamos; they are like Kedushas ha'Guf.

Chelkas Mechokek (EH 81:5): The Ran holds that she was not Makdish her hands to Shamayim, which is like Hekdesh Damim. It has Pidyon and does not uproot liens. Since it does not take effect now, it would not take effect after divorce. Saying 'this field is Hekdesh when I will buy it' does not work, for it is not is his control. Similarly, divorce is not in her control! Rather, she forbade only to her husband. This is like Kedushas ha'Guf, for there is no Pidyon. The Rambam holds that even Hekdesh to Shamayim takes effect.

Question (Ran 23b DH Tanan): Since the vow does not take effect until after divorce, how can he annul it? It is not Inuy Nefesh, nor Beino l'Veinah!

Answer (Ran): Mid'Oraisa, it is Hekdesh now. Chachamim strengthened a husband's lien, so it does not take effect until divorce. They strengthened his lien for his benefit, not for his detriment (to prevent him from annulling).

Ran (16b DH Omar): We need not say that she literally said that her hands should be Hekdesh. Since she mentioned her hands, it is as if she specified.

Poskim

Shulchan Aruch (YD 234:71): If a woman told her husband 'what I produce is forbidden to your mouth', he should annul this. Even though she is Meshubad to him, perhaps he will divorce her and be unable to remarry her. Therefore, even now it is considered Beino l'Veinah.

Rema: This is only if she said 'my hands are Kodesh to their Maker.'

Beis Yosef (YD 234 DH u'Mashma): It seems that she did not literally make her hands Hekdesh to Shamayim, for the Mishnah says 'to your mouth.' Rather, she said 'they are Kodesh to their Maker to you mouth', i.e. they are forbidden to your mouth like Hekdesh.

Shulchan Aruch (EH 81:2): If a woman said 'my hands are Hekdesh to their Maker', or vowed that her husband not benefit from her earnings, he is not forbidden, because her hands are Meshubad to him. However, he should annul her vow, lest he divorce her and be unable to remarry her.

Beis Yosef (DH v'Nir'eh): The Rosh explains that we conclude that she need not say that she forbids for after divorce. Even if she forbids Stam, mid'Oraisa it takes effect immediately, just Chachamim strengthened his lien during the marriage. However, a vow to forbid her earnings is void, for it is Lo Ba l'Olam.

Beis Shmuel (5): The Shulchan Aruch rules like the Rambam. We conclude that Konamos take effect on Davar she'Lo Ba l'Olam, and uproot liens mid'Oraisa. Alternatively, we asked that her hands are Meshubad to him according to Reish Lakish, who says that she cannot say 'don't feed me, and I will keep my earnings.' We hold that she can say this. In Yoreh De'ah, the Rema rules like the Ran and Rosh, that her vow is valid only if she made her hands Hekdesh to Shamayim. Why didn't he comment here?