Question: In Bava Basra (88a), we say that one who buys vegetables in the market... if he resolved to buy, he acquired, and he is obligated to tithe. He cannot return it unless he tithes it;

Inference: We do not sell Demai to an Am ha'Aretz!

Answer #1: Here we discuss selling to a Chaver (one who is trustworthy about Ma'aser).

Answer #2: Just like they permitted feeding Aniyim and guests Demai, so they permitted selling to a wholesaler and to a Ba'al ha'Bayis, when he sells a large amount.

Citation (Demai 5:3 - Mishnah R. Meir): One who buys from a baker [may] tithe from hot bread on cold, and from cold on hot, even from many molds;

Citation (cont. - R. Yehudah): He may not. I can say that the wheat for [the bread he made] last night were from one [seller], and [the wheat for] today's is from another!

Citation (5:4 - Mishnah - R. Meir): One who buys from a wholesaler tithes from every mold. R. Yehudah says, he tithes from one on everything.

Question #1: How could [Ravina] say "granted, from cold... however, why is it permitted from many molds?"

Just the contrary! From cold on hot is difficult, for [R. Meir] is more lenient than R. Yehudah, for R. Yehudah forbids;

However, regarding many molds he does not argue, like it teaches "I can say that the wheat for [bread of] last night was from someone else"! This implies that he argues only about cold [and hot].

Question #2: Even for [one who bought from] a wholesaler, in which case R. Meir forbids [tithing from one mold on another], R. Yehudah permits [tithing] from one on everything, and all the more so for a baker!

Answer: Our Mishnah means that one who buys from a baker tithes from hot on cold, even if the hot and cold are from many molds. So says R. Meir;

R. Yehudah forbids cold on hot when they are from many molds, for I can say that those of last night, i.e. the cold, were from someone else, since there is also a different mold than today's.

Support: Now, the Gemara asked properly. Granted, cold and hot from one mold is like R. Ila'i, who permits b'Di'eved for Vadai [Tevel], therefore for Demai he may tithe even l'Chatchilah;

However, when the hot and cold are from different molds, why is it permitted? R. Yehudah forbids in this case!

Inference: R. Meir is more lenient [about Demai] than Rabanan.

Explanation: Ravina properly knew that R. Meir forbids regarding a wholesaler, because he buys from two or three [sellers]. However, even so he asked because R. Meir is more lenient than Rabanan.

Abaye answered that R. Meir's reason does not depend on leniency and stringency, rather, on what is common;

The custom is that a baker buys [grain] from one person, and sometimes he buys two kinds of grain, and everything is from one person. He makes [bread from] them in two molds, in order to know which is from the bad grain, and which is from the good.

R. Yehudah holds that since it is hot and cold, and also from different molds, it is proven that he bought from two people;

However, just due to different molds, even for a wholesaler, R. Yehudah is not concerned.

Question: Perhaps he bears sin because he eats without another separation!

Answer: The verse connotes that he bears sin due to the separation alone.

Inference: Since [the verse] excludes [documents] from Ona'ah, this connotes that mid'Oraisa, the sale takes effect.

Question - Citation (Bava Basra 147b): Matanas Shechiv Mera is mid'Rabanan;

Citation (cont.) Question: Rav Nachman taught that if one sold a document to his friend, and then [the seller] pardoned it, it is pardoned. Even an heir [of the seller] can pardon;

Citation (cont.): Rav Nachman agrees that if he gave it through Matanas Shechiv Mera, he cannot pardon it.

Citation (cont.): Granted, if you will say that Matanas Shechiv Mera is mid'Oraisa, therefore he cannot pardon...

Summation of question: Sale of a loan document is mid'Oraisa, and even so he can pardon!

Answer #1 (Ri): It means as follows. Granted, if you will say [that Matanas Shechiv Mera is] mid'Oraisa, i.e. from "v'Ha'avartem", if so the verse made [the recipient] an heir. If so, why can an heir pardon? Why is this heir [of the lender, who gave the document through Matanas Shechiv Mera] better than this [heir, i.e. the recipient]?...

Answer #2: Even if sale of a loan document were mid'Rabanan, Ona'ah can apply mid'Oraisa, e.g. he lent to him without a document, and [the lender] gave to him too much in order to make a document to put a lien [on his land];

Alternatively, he lent to him with a document, and the borrower gave to him too much to return the document, so it will be a Milveh Al Peh (a loan without a document).

Answer #3 (R. Chaim Kohen): It seems that he acquired mid'Oraisa if the borrower has land. He sells to him a lien that he has in the land. In Bava Kama (62b) I elaborated.

Question: In Avodah Zarah (15a) it is proven that rental does not acquire, from a Yisrael who rented a cow from a Kohen (he may feed it vetch of Terumah. This shows that it still belongs to the Kohen), and [even where one may rent houses to Nochrim, he may] not [rent] for dwelling [lest the Nochri bring in his idols. This would be idols in the Yisrael's house!]

Answer: Here, regarding Ona'ah, an extra "Memkar" is written to include rental.

Inference: Here it connotes that Rava discusses even land.

Support: Also in Kidushin (42b) he said "also regarding [brothers who divided] land, we said [that there is no Ona'ah] only when they divided based on estimation [of value], but if they divide according to area, an error even less than the Shi'ur of Ona'ah is returned;

Citation (42b - Rava): Anything measured [if they erred about the measure] is returned.

"Is returned" means that the sale is totally Batel, like is proven in Menachos (77a) and Bava Basra (90a).

Question: In Bava Basra (104a), a Mishnah says "I sell to you a Beis Kor of earth, measured by a rope', if it is any amount less, he deducts [from the price]. If it is any amount more, he returns the extra";

The Rashbam explained that Rava's teaching that it is returned does not refer to land. Our Gemara opposes this!

Answer: There, the seller does not say "I measured that there is a Beis Kor." Then, surely it is returned, like Rava taught;

Rather, he says so Stam. The seller thought that there is this amount, therefore the sale stands.

Question: (Below, Rava asked whether or not Ona'ah applies to wheat planted in the ground, and the Gemara asked what is the case.) We should say that he knows that he planted six measures, and sells it for more than its value. Perhaps it is Batel to the ground!

Answer: In such a case, obviously there is Ona'ah. The error does not depend on the land, rather, on [the price of] wheat in the market.

Question: This is a Mekach Ta'os, for it needs six, and he planted only five!

Answer: The seller admits that he planted only five, and says that it needs only five. This land, if he planted it properly, is worth the money [he charged]. It turned out that it needed six.

Question: Why isn't this considered Ona'ah of land, since he did not err about the amount of wheat, and not value? He erred only that the land did not improve properly!

Answer: Since had he planted it properly, like he said, it would have been worth the money, it turns out that the Ona'ah is in the wheat, and not in the land.