Talmud - Bava Metzia 47a בבא מציעא מ״ז א׳

And if the sum of money is one-sixth lower than the value of the item, the seller of the item has a claim of exploitation against the buyer, who must pay the difference to the seller.

The Gemara elaborates: The buyer acquires the item even though he did not pull it, because since the seller is not particular about the sum, the buyer acquired the item, as it is similar to a transaction effected by means of exchange. And the seller has a claim of exploitation against the buyer because the buyer said to him: Sell me your item for these coins. The use of the language of sale indicates that it will be for an acceptable price. Rav Abba says that Rav Huna says that if the buyer said: Sell me your item for these coins, the buyer acquired the item; and the seller of the item has no claim of exploitation against the buyer, as it is a full-fledged transaction effected by means of exchange.

The Gemara analyzes these halakhot: It is obvious that in a case where there is a sale of an item for money and the seller is not particular about the sum, we say that the buyer acquires the item immediately upon receiving the money, as it is similar to a transaction effected by means of exchange. But if it is a transaction effected by means of exchange and one of the parties is particular that the value of the items is equal, what is the halakha? Is its legal status that of a sale, or that of a transaction effected by means of exchange?

Rav Adda bar Ahava says: Come and hear a resolution to the dilemma from a baraita: There is a case where one was grasping his cow and standing in place, and another came and said to him: Why is your cow standing here? The owner of the cow replied: I need a donkey, and I hope to exchange this cow for one. The other person said: I have a donkey that I can give you; for how much are you selling your cow? The owner of the cow responded: I am selling it for such and such a price. He then said: For how much are you selling your donkey? The owner of the donkey responded: I am selling it for such and such a price.

If, after this discussion, the owner of the donkey pulled the cow, but the owner of the cow did not manage to pull the donkey before the donkey died, the owner of the donkey did not acquire the cow, even though ostensibly this was a transaction effected by means of exchange, which is typically complete once one of the parties pulls the item he is acquiring.

The Gemara suggests: Learn from it that in a case where there is a transaction effected by means of exchange and one of the parties is particular that the value of the items is equal, he does not acquire the item immediately. In contrast to the standard case of exchange, the owners of the cow and donkey assessed the value of the animals before the transaction. Since they are particular about the price, the acquisition is not completed until each pulls the item he is acquiring.

Rava said: Is that to say that in a standard case of exchange we are dealing with fools, who are not particular about the value of the items that they are acquiring? Rather, in every case of exchange, the parties are particular about the value of the items, and when one party pulls an item the other party acquires the other item immediately and pays for it later. And with what are we dealing here? The case in the baraita is where one party said to the other party: Let us exchange a donkey for a cow and a lamb, and the owner of the donkey pulled the cow and did not yet pull the lamb, as in that case he has not performed a proper act of pulling.

The Master, Rav Huna, said above that if one said to another: Sell me your item for these coins, the buyer acquired the article, and if the sum of money is one-sixth lower than the value of the item, the seller of the item has a claim of exploitation against the buyer. The Gemara suggests: Let us say based on that halakha that Rav Huna holds that a coin can be an item used to effect exchange.

The Gemara rejects this suggestion: No, Rav Huna holds in accordance with the opinion of Rabbi Yoḥanan, who says: By Torah law money effects acquisition. And for what reason did the Sages say that pulling acquires an item and money does not? This is a rabbinic decree lest the seller say to the buyer after receiving the money: Your wheat was burned in the upper story. And it is only with regard to a common matter that the Sages issued a decree, but with regard to an uncommon matter the Sages did not issue a decree. Therefore, in this case there is no decree, and the transaction is governed by Torah law. Mar Huna, son of Rav Naḥman, said to Rav Ashi: You teach this halakha in that manner; we teach it in this manner, not by inference but as an explicit ruling: And likewise, Rav Huna said: Money cannot be the item used to effect a transaction by means of exchange.

§ Above, the Gemara mentioned a form of exchange in which there are not two items of equal value being exchanged, but rather one person attempts to transfer possession of his item to the buyer by means of a symbolic exchange involving, e.g., a cloth. With regard to that symbolic transaction, the Gemara asks: With what vessel does one acquire the item in question, i.e., whose vessel is used in order to effect this symbolic transaction?

Rav says: One effects the transaction with the vessels of the one acquiring the item, who effects the transaction by giving the vessels to the owner of the item. The moment that the owner pulls the vessel into his possession, the transaction is complete and ownership of the item in question is transferred to his counterpart. Rav explains that the one acquiring the item is amenable to having the one transferring ownership of the item acquire his vessel, so that he will resolve to transfer ownership to him. And Levi says: One effects the transaction by having the one acquiring the item pull the vessels of the one transferring ownership, as we seek to explain below.

Rav Huna from Diskarta said to Rava: But according to Levi, who says that one effects the transaction with the vessels of the one transferring ownership, there is a difficulty. In a case where one acquires land by means of symbolic exchange where the item used is a cloak, it turns out that he is acquiring land by means of a cloak. If so, this is a case of property that is guaranteed, i.e., land, and it is acquired with movable property that is not guaranteed, by means of a transaction performed on the latter. And we learned the opposite in a mishna (Kiddushin 26a): Property that is not guaranteed is acquired with property that is guaranteed, i.e., land, by means of a transaction performed on the latter.

Rava said to him: If Levi, whose opinion you questioned, were here, he would take out rods of fire before you and flog you for your unwarranted question. Do you maintain that he said that at the moment he transfers ownership of the cloak he transfers ownership of the land to him? That is not the case; rather, in exchange for that pleasure the owner of the item experiences from the fact that the one acquiring the cloak accepted it from him, he resolves to transfer ownership to him. This is unlike the acquisition of movable items by means of a transaction of land, where both are acquired simultaneously. Here, the transfer of ownership of the cloak effects the subsequent transfer of ownership of the land.

The Gemara comments: This dispute between Rav and Levi is parallel to a dispute between tanna’im. The verse states: “Now this was the custom in former time in Israel concerning redemption and concerning substitution, to confirm all matters; a man drew off his shoe, and gave it to his neighbor” (Ruth 4:7). The verse is interpreted: “Redemption”; that is a sale. And likewise it says: “Neither shall be sold nor shall be redeemed” (Leviticus 27:28). “Substitution”; that is the transaction of exchange. And likewise it says: “He may neither exchange it nor substitute it” (Leviticus 27:10).

With regard to the phrase “To confirm all matters; a man drew off his shoe, and gave it to his neighbor,” the baraita asks: Who gave the shoe to whom? Boaz gave his shoe to the redeemer, the closest relative of Elimelech, who had the right of first refusal to the land that Naomi, Elimelech’s widow, was planning to sell. The redeemer was transferring that right to the land to Boaz, who was acquiring it by means of his shoe. Rabbi Yehuda says: The redeemer gave his shoe to Boaz. The dispute between Rav and Levi is parallel to the dispute between the first tanna and Rabbi Yehuda.

§ It was taught: One can acquire property through a symbolic exchange by using a vessel, even if it does not have the value of one peruta. Rav Naḥman says: The Sages taught that this symbolic exchange can be effected only by using a vessel, but not by using produce, i.e., any item other than a vessel. Rav Sheshet says: It can be effected even by using produce. The Gemara explains: What is the reason for the opinion of Rav Naḥman? The verse states: “His shoe” (Ruth 4:7), from which it is derived: With regard to a shoe and any other item similar to a shoe, i.e., a vessel, yes, the symbolic exchange can be effected; with regard to any item other than a vessel, no, it cannot be effected.

What is the reason for the opinion of Rav Sheshet? The verse in Ruth states: “To confirm all matters,” from which it is derived that all items, even if they are not vessels, can effect the exchange. The Gemara asks: According to Rav Naḥman as well, isn’t it written: “To confirm all matters”? The Gemara explains: In his opinion, that phrase: “To confirm all matters,” is referring to all items that can be acquired through an exchange effected by using a shoe. The Gemara asks: And according to Rav Sheshet as well, isn’t it written: “His shoe”? The Gemara explains: Rav Sheshet could have said to you that from that term it is derived: Just as his shoe is a complete item, so too, every complete item can effect a symbolic exchange, to exclude half a pomegranate and half a nut, which cannot effect a symbolic exchange. A whole pomegranate or nut can be used for that purpose.

Rav Sheshet, son of Rav Idi, said: In accordance with whose opinion do we write today in documents that the transaction was effected with a vessel that is fit to acquire items with it? The Gemara explains: The term with a vessel serves to exclude the opinion of Rav Sheshet, who says: One acquires an item through a transaction of symbolic exchange by using produce. The term that is fit serves to exclude the opinion of Shmuel, who says: One acquires an item

Traduction : The William Davidson digital edition of the Koren Noé Talmud, with commentary by Rabbi Adin Even-Israel Steinsaltz.

BavaMetzia 47a examines exchange transactions versus sales, exploring when payment or barter finalizes ownership and how price discrepancies trigger exploitation claims.