Gemara

Kidushin 22b (Mishnah - R. Meir): A Kena'ani slave can acquires his freedom through money given by others.

Chachamim say, he acquires his freedom through money he gives himself, as long as it is of others.

23b (Rabah): All agree that anything that if a slave or wife acquires something, it belongs to the Ba'al (master or husband). The Mishnah discusses when one told the slave 'acquire this money on condition that your master has no rights to it';

R. Meir holds that once he says 'acquire', the slave acquires and it belongs to the master. The continuation of his words, 'on condition that your master has no rights to it', has no effect. Chachamim say, his stipulation takes effect.

Objection (R. Elazar): If that were the stipulation, all would agree that the slave acquires and it belongs to the master! Rather, he said 'acquire it on condition that you will be freed through it.' R. Meir holds like Rabah said. Chachamim say, the giver limited the acquisition. The slave acquires the money only for freedom.

Contradiction (Beraisa): A woman who redeems Ma'aser Sheni must always add a fifth of the value;

R. Meir says, she can redeem it without adding a fifth.

The case is, she received money 'only in order to redeem the Ma'aser.' R. Meir says that the stipulation works. Chachamim say that the money belongs to her husband. This is the opposite of their opinions about a slave!

Answer #1 (Abaye): We must switch the opinions (in the Beraisa).

Answer #2 (Rava): The text is correct. The case is, she inherited the Ma'aser from her father (and redeemed it with her husband's money). R. Meir holds that Ma'aser Sheni is like Hash-m's money, so her husband does not acquire it.

Nedarim 88a (Mishnah): If Reuven vowed not to benefit his son-in-law, he can give money to his daughter 'on condition that your husband has no Reshus over it. It is only for you to buy food with it and to eat the food.'

(Rav): This is only if he says 'it is given only for you to buy food with it and to eat the food.' If he says 'do like you want with it', her husband acquires the money.

(Shmuel): In either case, her husband does not acquire the money.

Rishonim

Rif (Kidushin 8a): The Halachah is, a slave or married woman can acquire only for his or her Ba'al. A slave can pay to go free only with money given to him on condition that it is for his freedom. The master acquires it only for freedom.

Question (Ran 8b DH b'Kesef): The Rif cites R. Elazar, who holds that Chachamim agree that 'on condition that your husband has no Reshus over it' does not help, and R. Meir holds that even a stipulation for a particular use does not help. In Nedarim, R. Meir holds that such a stipulation helps, and Chachamim hold that 'on condition that your husband has no Reshus helps!

Answer (Ran): R. Tam rules like Rabah because the Sugya in Nedarim is like Rabah, and unlike R. Elazar. R. Elazar holds that Rav holds like Chachamim, and Shmuel is unlike any Tana. (Shmuel disagrees with R. Elazar.)

Question: If R. Meir agrees that saying 'on condition that you go free with the money' helps, why does he require that the money be of others?

Answer (Ran): Also this is called 'of others'.

Question: The Rif rules like R. Elazar. If so, the contradictions in R. Meir and Chachamim remain, and there is also a contradiction in the Halachah!

Answer (Ran): R. Elazar said that 'on condition that you go free with the money' does not help for a slave. It helps for a wife, who is less obligated to her Ba'al and has more power to acquire. The Gemara asked from a wife to a slave about a stipulation that the Ba'al has no Reshus over it. Regarding this, we do not distinguish a slave from a wife. R. Meir holds that 'on condition that you go free with the money', or 'that you use it to redeem the Ma'aser' helps only if he also stipulated that the Ba'al has no Reshus over it.'

Rambam (Hilchos Zechiyah 3:13): If one gave a gift to a woman on condition that her husband has no Reshus over it, her husband acquires. However, if he stipulated that the gift is for something specific, her husband does not acquire.

Ran (Nedarim 88b DH ul'Inyan): Rav Amram Gaon and the Ramban rule like Shmuel, because this hinges on a monetary law, i.e. whether or not her Yad is like his. Also, we follow Chachamim against R. Meir. Also, the Gemara in Nazir and Sanhedrin says only 'on condition that your husband has no Reshus', like Shmuel. The Ra'avad and R. Tam rule like Rav. The Rambam rules like Shmuel, but he holds that even Shmuel requires saying 'do what you want with it.' Rav and Shmuel argue about whether or not he must say precisely 'it is given only for what you will eat.'

Rosh (Kidushin 1:29): The Gemara mentioned slaves with women, for according to the opinion that a slave can acquire, all the more so a wife can. According to Rabah, R. Meir holds that a slave can never acquire for himself. Saying 'on condition that your Ba'al has no Reshus' is like giving a gift and saying 'it is yours, on condition that it is not yours.' A self-contradictory Tanai is Batel. The Stam Gemara in Sanhedrin, Pesachim and Nazir is like Rabah. Even though the Halachah follows R. Meir, these Gemaros said only 'on condition that your Ba'al has no Reshus' to teach that the Halachah follows Rabah. It is clear that R. Meir also requires 'it is only for you to...'

Poskim

Shulchan Aruch (EH 85:11): If one gave a gift to a married woman 'on condition that your husband has no Reshus over it', he acquires, and it is like Nichsei Melug. He does not acquire if the giver specified that it is for a specific matter, e.g. on condition that you will wear it or do what you want without his Reshus.

Bedek ha'Bayis: We follow most Poskim, who rule like Shmuel. It is best to add 'do what you want with it' to fulfill the Rambam's opinion.

Question (Chelkas Mechokek 26): Why does the Shulchan Aruch rule against Tosfos, the Rosh, Maharam, Avi ha'Ezri, and Ra'avad? We should be concerned for their opinion, especially if the husband is Muchzak!

Beis Shmuel (23): Here, the Shulchan Aruch rules like the Rambam because most Poskim hold that it suffices to say 'on condition that your husband has no Reshus, only do what you want with it.' However, if the husband seized it, he can say that he holds like those who disagree. In Yoreh De'ah, regarding Isur (Nedarim), the Shulchan Aruch is stringent for Tosfos' opinion.