Gemara

98a (Mishnah): If a widow's Kesuvah was 400, and she sold 100, 100, 100, and then land worth 101 for 100, the last sale is void, and the other sales stand.

98b (Version #1) Question: If Levi told a Shali'ach to sell for him (land fitting to sow) 15 Sa'im and the Shali'ach sold 30, what is the law?

Did he fulfill his mission and add to it, therefore the sale of 15 stands?

Or, did he deviate from his mission, and the sale is totally void?

99a (Version #2): If he told a Shali'ach 'sell for me (land fitting to sow) 15 Sa'im' and the Shali'ach sold 30, clearly he fulfilled his mission and added to it;

Question: If he told him 'sell for me 30' and he sold 15, what is the law?

Can the Shali'ach say 'I did even better than you requested! Now, if you will not need the full amount of money, you will retain half the land!'

Or, can the owner say 'I do not want many documents against me?

Answer #1 (R. Chanina from Sura - Mishnah): Levi gave to Shimon a gold Dinar to buy a cloak. Shimon spent half the money for a cloak, and half for a Talis. If the money was found to be Hekdesh, both transgressed Me'ilah.

This shows that he adds. If buying half is deviating, why did Levi transgress?

Rejection: Shimon spent half the Dinar and bought a cloak worth a full Dinar.

Answer #2 (Mishnah): If her Kesuvah was 400, and she sold 100, 100, 100, and 101 for 100, all sales except for the last stand. (I.e. a smaller sale is valid.)

Rejection: The case is like Rav Shisha brei d'Rav Idi said (below), the orphans inherited small plots of land (that are not normally sold to one buyer).

Obviously, if he said 'sell to one buyer, not to two', a sale to two is invalid.

Question: If he said only 'sell to one person', if he sold to two, what is the law?

Answer #1 (Rav Huna): Here also, he meant 'sell to one buyer, not to two.'

Answer #2 (Chisda, Rabah bar Rav Huna and Rav Nachman): He meant 'sell to one, or even to two, or even to 100.'

Support (for Rav Nachman - Mishnah): ...If she sold 100, 100, 100, and 101 for 100, all sales except for the last stand. (If selling to too many buyers invalidates a sale, her sale should be void, to protect the orphans!)

Rejection (Rav Shisha brei d'Rav Idi): The case is, the orphans inherited small plots of land.

Rishonim

Rif: If a Shali'ach was told to sell 15 Sa'im of land, and he sold 30, did he fulfill his mission and add to it, and the sale of 15 stands? Or, did he deviate, and the sale is totally void? In Version #2, we are sure that he added. We ask about when he was told to sell 30, and he sold 15. Did he do even better than requested? Or, can the owner say 'I do not want many documents against me'? This was not settled explicitly. It seems that he deviated; it is invalid.

Rebuttal (Ba'al ha'Ma'or): The Rif rules that selling half is deviating. How can he validate a sale to 100, like Rav Nachman? Rather, the Halachah follows Rav Nachman; 'I do not want many documents' is not a valid claim. The last question assumes that a sale of half is valid. We ask, is this even if he cannot sell the rest to the same buyer? Or, can the owner say 'I do not want many litigants (buyers)'?

Rejection (Milchamos Hash-m): The Gemara would not leave the question unsettled, and later settle it! It should have said 'if you will say that ...'! It did not distinguish whether or not the same buyer bought both times! Rather, the questions are independent. The last question is about selling to two buyers, e.g. brothers or partners, in one document. Rav Nachman answers that since there is only one documents, we are not concerned for many litigants. The Rif and R. Chananel rule that selling too little is deviation. This is because we said that Levi transgressed Me'ilah when Shimon bought a cloak worth a Dinar for a half Dinar. It did not say that he bought a half Dinar cloak for a half Dinar. We infer that Levi would be exempt, because Shimon deviated.

Ran (DH Iboi): The question of selling half is when there is another buyer prepared to buy the other half for the same price.

Rosh (11:15): R. Chananel's text (like our text of the Rif) reads 'if he said 'sell to one', obviously a sale to two is invalid. If he said Stam, what is the law? Rav Chisda said 'to one, and even to two or 100', not because the owner said 'to one'. Rather, it is because Rav Huna said 'to one.

Rambam (Hilchos Sheluchim 1:4): If Levi told a Shali'ach to sell 30 Sa'im of land, and he sold 60, he added to his mission. The buyer acquires only 30. If he told him to sell 60, and he sold 30, he deviated, and it is invalid. If Levi told him to sell to one man, and he sold to two, he deviated, so it is invalid. If he told him 'sell my field' without specifying, even if he sold to 100, it is valid.

Rosh (11:15): In Version #2, surely when the Shali'ach sold too much, the buyer acquires if he wants. However, the buyer can say that he wants the entire sale, or not at all. Rather, we ask about one who sold too little. We could have asked about selling the full amount to two people. Even though the Shali'ach cannot say 'I did better than you asked', the question is whether or not he did badly. He does not need a claim that he did even better. We tried to bring a proof from a Shali'ach who bought a cloak and a Talis. He did not do extra good, for he spent the entire amount! Also, selling to two is called 'adding to his words.' Selling only half is not 'adding'. This was not settled explicitly, but it seems that he deviated. If not, even if he bought a (Hagahos Tif'eres l'Moshe - half) Dinar cloak for a half Dinar, Levi would be liable! Also, since the question was not resolved, we leave the money in its Chazakah; the buyer did not acquire. Also, the claim 'I do not want many documents' appears throughout Shas.

Question: The Gemara didn't settle whether or not 'I don't want many documents' is a proper claim. Why is Rav Chisda sure that one may sell even to 100?

Answer (R. Tam, cited in Rosh): 'I do not want many documents' is not due to cheapening his property. Rather, it is a toil to get witnesses and do a Kinyan (Chalipin) for each. The Amora'im argue about when the Shali'ach did this, and the only concern is many litigants. Alternatively, he sold to two people in one document. The Gemara tries to learn from a widow who sold in many documents. It is valid, and all the more so when a Shali'ach sells in one document. The Rif rules that selling half is deviating, but a sale to two is valid. He must answer like R. Tam. Rav Hai rules that selling to two is adding to his words. He explains 'Pshita' to mean 'we now settle our question' (and not 'the following is obvious').

Beis Yosef (CM 182 DH v'Chosvu ha'Tosfos): Alternatively, Rav Hai explains that the last question was 'if you will say that selling half is valid...'

Poskim

Shulchan Aruch (CM 182:8): If Levi told a Shali'ach to sell 30 Sa'im of land, and he sold 60, he added to his mission. The buyer acquires only 30. However, the buyer can say that he wants to buy all 60 (or not at all).

Shulchan Aruch (9): If he told him to sell 60, and he sold 30, he deviated, and it is invalid.

Shulchan Aruch (10): If he told him to sell to one man, and he sold to two, he deviated, and it is invalid.

Question (Beis Yosef DH v'Divrei): Why does the Tur say that the Rif holds that it is valid in this case? According to the Rif's text, he deviated!

Answer #1 (Drishah 14 DH Achen): Tosfos and the Rosh say that this was R. Chananel's text; they do not cite the Rif's text. It seems that the Rif explains that Rav Huna says 'Pshita, if he said to one...', but Rav Chisda disagrees.

Answer #2 (Bach DH u'Svira): The Rif explains 'Pshita, if he said 'to one', he wants only one document. Was he also particular about only one buyer?'

Rema: Some say that this is only if he sold in two documents.

Shulchan Aruch (11): If he told him 'sell a field' without specifying, even if he sold to 100, it is valid. This is if he sold in one document, or in many documents and the Shali'ach got witnesses to sign them. If he sold in two (or more) documents and did not get witnesses to sign them, it is invalid.

Question (SMA 19): Why didn't the Shulchan Aruch and Rema bring the Ri's opinion, that it depends only on the number of documents? This fits the Gemara better. The Darchei Moshe (6) cites the Rif!