Gemara

A woman about to have Nisu'in wanted to divert her property from her husband. She wrote a document giving her property to her daughter, had Nisu'in, and was divorced. The document came in front of Rav Nachman; he tore it up.

Rav Anan (to Mar Ukva, the Av Beis Din). Nachman tears up people's documents (improperly)!

Mar Ukva: Do you discuss a Shtar Mavrachas (a document to divert property)? Shmuel said that he would tear up such a document!

Question (Rava, to Rav Nachman): Did you tear it up because surely, a person would not abandon himself and give his money to others? That applies to others, but one does give to his daughter!

Answer (Rav Nachman): A person takes precedence over his daughter.

Question (Beraisa - R. Shimon ben Gamliel): If one wants to divert property from her husband, she writes to someone else a Shtar Pasim (she appeases the recipient to accept the property to divert it from her husband);

Chachamim say, the recipient can keep the property and laugh at her, unless she wrote 'from today until I want.'

Inference: If she did not write this, the document is valid!

Answer (R. Zeira): If she gave all her property, it is invalid even if this was not written. If she gave only part, it is valid unless the clause was written.

Question: If the recipient does not get the property, the husband should get it!

Answer (Abaye): It is considered like property unknown to the husband. This is like R. Shimon (who says that the husband does not get unknown property).

Gitin 40a: A case occurred in which two partners had a slave. One freed his half. The other feared lest Chachamim find out and force him to free his half. (There was an enactment to free half-slaves). To prevent this, he transferred ownership of his half to his son, who was a minor (and unable to free him).

Rav Papa: We make his scheme backfire! Appoint an overseer, get the child to agree to free the slave in exchange for some coins, and write a document of freedom in the child's name.

Rishonim

Rif and Rosh (7:2): Leah wrote a document giving her property to her daughter before Leah's Nisu'in, to divert her property from her husband. After she was divorced, she and her daughter came in front of Rav Nachman. He tore up the document, for one does not abandon himself and give away his property, even to his daughter.

Rif: Chachamim say that if one wrote a Shtar Pasim to divert property from her husband, the recipient can keep it, unless she wrote 'from today until I want.' We answer that that is when she gave part of her property. If she gave all her property, in any case she gets it back. Her husband does not get the property, for it is like property unknown to the husband, according to R. Shimon. This shows that the Halachah follows R. Shimon.

Rosh (ibid.): When she gives everything, we assess that she did not abandon herself. We say the same about a Shechiv Mera who gave away all his property. Likewise, if she married immediately after the gift, we assume that the gift was only to deny her husband rights to Peros and inheritance. The recipient eats the Peros until she sells them, or until she is widowed or divorced. If the Peros belonged to her, her husband would buy land with them and eat its Peros. Also, she knows that the recipient will not care for the field properly unless he gets the Peros. If she dies before her husband, the recipient keeps it. If not, her husband would inherit it, and she did not want this! If her husband died, and then she died before retracting from the sale, the property reverts to her heirs, for we follow our assessment that she intended only to divert. This is like a Shechiv Mera who recovered from his illness, then died. Once he recovered, his gift was Batel. The Shiyur (the amount she must leave for herself to show that this is a proper gift) is the same as for Shechiv Mera, like I explained in Bava Basra (below)

Hagahos Ashri (citing the Mordechai): My Rebbi says that Mavrachas does not acquire only if she retracted, but if she died, the recipient acquired. He proves this from Gitin 40a, in which they induced a child to free his half-slave. The child acquired because his father did not retract. I say that this is not a proof, for it was a partial gift. Even Metaltelim are a remnant (that prevents it from being Mavrachas)! Nevertheless, if it is clear that she intended for Mavrachas, it is as if she wrote 'from today until I want.'

Rosh (2,3): Rashi says that the Gemara asked 'if the daughter did not acquire, how is this Mavrachas?' I.e., the daughter or husband must acquire. Since she did not want her husband to acquire, we must say that her daughter acquires. There were cases of Mavrachas to avoid a lien on land to pay a debt and a Kesuvah. R. Shimshon says that R. Tam ruled that these are proper gifts. When a woman writes a Shtar Mavrachas before marrying, this is so the husband will not get the property. It suffices to make the property as if it is unknown to him. To avoid a lien, it must be a proper gift. If not, it is not Mavrachas! I disagree. Shmuel said that Mavrachas never acquires. The Gemara asked 'if so, the husband should acquire!', and answered. In other cases, e.g. to avoid a lien, we also say that one does not abandon himself. However, then the diversion does not help, and the lien takes effect. It is called Mavrachas because the giver thought that it will help. Since he did not intend to really give it, the property stays with him and the lien takes effect. Also, this law is based on estimation. Surely he prefers to eat Peros of his property until the creditor collects it, rather than lose his property and be a Rasha who borrows and does not pay. Also, if the gift is invalid, if he outlives his wife he will keep the property permanently. The Ramah and other Gedolim say so.

Rosh (Bava Basra 9:26): The Gemara said that any amount is a Shiyur for Matanas Shechiv me'Ra. Rav Yehudah says that this means enough land to support himself, i.e. if he is a farmer. R. Yirmeyah says that it is enough Metaltelim to support himself, i.e. if he is a businessman. Rav Yosef questioned them, but no one gives a different Shiyur. Why does the Rif say that any amount is a Shiyur?! Surely we follow the Amora'im's Shi'ur! Also, it is reasonable that one leaves himself enough to survive!

Rambam (Hilchos Ishus 22:9): If before marrying, a woman wrote a document giving all of her property to a relative or a stranger, if she is widowed or divorced, the gift is Batel. Nevertheless, her husband does not eat the Peros, and does not inherit it if she dies, for she gave it before marrying. When she dies, the recipient acquires it totally.

Rambam (Hilchos Zechiyah 6:12): She gave the gift only so that her husband will not inherit it, and it will return to her when she needs it. Therefore, if she dies in her husband's lifetime, the recipient acquires it totally. If she left anything over, even Metaltelim, the gift stands. Even if she was divorced, it does not return.

Poskim

Shulchan Aruch (EH 90:7): If before marrying, a woman wrote a document giving all of her property to a relative or a stranger, if she is widowed or divorced, the gift is Batel. Nevertheless, her husband does not eat the Peros, and does not inherit it if she dies, for she gave it before marrying. When she dies, the recipient acquires it totally.

Chelkas Mechokek (20): The Tur rules like the Rosh, that if she did not leave herself enough property to support herself, this is a total gift. The Shulchan Aruch did not give a Shi'ur. He rules like the Rif and Rambam, who say that a Matanas Shechiv me'Ra with any Shiyur is like a gift of a healthy person.