Talmud - Bava Metzia 50b בבא מציעא נ׳ ב׳

and according to Rabbi Tarfon too, there is a waiver of the disparity of less than one-third and the transaction is finalized immediately, why did they revert to following the statement of the Rabbis? In that case, the ruling of Rabbi Tarfon would be preferable for them, as that which the Rabbis deem exploitation, i.e., a discrepancy of one-sixth, is waived according to Rabbi Tarfon.

The Gemara rejects this proof: Do you maintain that the legal status of a disparity of less than one-third according to the opinion of Rabbi Tarfon is like the legal status of a disparity of less than one-sixth according to the opinion of the Rabbis? No, the legal status of a disparity ranging from one-sixth until one-third according to the opinion of Rabbi Tarfon is like the legal status of a disparity of one-sixth itself according to the opinion of the Rabbis, and the exploited party receives the sum of the exploitation in return. The Gemara asks: If so, for what reason did the merchants of Lod rejoice initially? They gained nothing relative to the ruling of the Rabbis.

Resolve, based on this difficulty, the dilemma raised below, and conclude that in cases of nullification of the transaction according to the Rabbis, one may always renege on the transaction. Therefore, the reaction of the merchants of Lod is understandable, as, since Rabbi Tarfon said to them that a disparity between one-sixth and one-third is merely exploitation, they rejoiced, as this would mean that the buyer has only the time it takes to show the merchandise to a merchant or a relative to renege. When he said to them that the exploited person can renege on the transaction for the entire day, they reverted to following the statement of the Rabbis.

The Gemara explains why the dilemma is resolved: As, if it enters your mind to say that nullification of the transaction according to the Rabbis is limited to only within the time that it takes for the buyer to show the merchandise to a merchant or to his relative, for what reason did they rejoice over the ruling of Rabbi Tarfon? His ruling did not enable them to sell the merchandise at a higher price than the ruling of the Rabbis did. The Gemara rejects this proof: They initially rejoiced over the case of a disparity of one-sixth itself, as according to Rabbi Tarfon there is a waiver of the disparity, and according to the Rabbis it is exploitation.

§ The Gemara cites the dilemma referenced above. A dilemma was raised before the Sages: With regard to nullification of the transaction according to the Rabbis, may one always renege on the transaction? Or perhaps he can renege only within the time that it takes him to show the merchandise to a merchant or to his relative. And if you say that the transaction is nullified only within the time that it takes him to show the merchandise to a merchant or to his relative, what difference is there between a disparity of one-sixth and a disparity of greater than one-sixth? The Gemara answers: There is a difference, as in the case of a disparity of one-sixth, only the one who was exploited can renege on the transaction, while in the case where the disparity is greater than one-sixth, both can renege on the transaction.

The Gemara returns to discuss the dilemma: What is the halakha? The Gemara suggests: Come and hear a resolution of the dilemma from the mishna: The merchants of Lod reverted to following the statement of the Rabbis. Granted, if you say that one can claim nullification of the transaction according to the Rabbis only within the time that it takes the buyer to show the merchandise to a merchant or to his relative, and according to Rabbi Tarfon one can do so for the entire day, it is due to that reason that they reverted to following the statement of the Rabbis. But if you say that one can claim nullification of the transaction according to the Rabbis and always renege on the transaction, why did they revert to following the statement of the Rabbis? In that case, the ruling of Rabbi Tarfon is preferable for them, as he deems such a disparity exploitation and rules that one can claim nullification of the transaction for the entire day and no more, which is more beneficial to the merchant.

The Gemara answers: Nullification of the transaction is uncommon, and therefore the merchants of Lod did not take that into consideration when calculating which ruling was most advantageous.

The Gemara cites the halakhic resolutions of these dilemmas. Rava said: The halakha is that if the disparity is less than one-sixth, the merchandise is acquired immediately. If the disparity is greater than one-sixth, either party can demand nullification of the transaction. If the disparity is precisely one-sixth, the buyer has acquired the merchandise, and the one who benefited from the exploitation returns the sum gained by the exploitation. And one may claim both this, nullification of the transaction, and that, return of the sum gained, only within the time that it takes to show the merchandise to a merchant or to his relative.

The Gemara comments: It is taught in a baraita in accordance with the opinion of Rava: In cases of exploitation, if the disparity is less than one-sixth, the merchandise is acquired immediately. If the disparity is greater than one-sixth, the transaction is nullified. If the disparity is precisely one-sixth, the buyer has acquired the merchandise, and the one who benefited from the exploitation returns the sum gained by the exploitation. This is the statement of Rabbi Natan. Rabbi Yehuda HaNasi says: In a case where the seller was exploited, the seller is at an advantage. If he wishes, he reneges on the transaction and says to the buyer: Give me my merchandise, or he can say: Give me the sum that you gained by exploiting me. And one may claim both this, nullification of the transaction, and that, return of the sum gained, only within the time that it takes to show the merchandise to a merchant or to his relative.

§ The mishna teaches: Until when is it permitted for the buyer to return the item? He may return it only until a period of time has passed that would allow him to show the merchandise to a merchant or to his relative. Rav Naḥman says: The Sages taught this halakha only with regard to a buyer, but a seller may always renege on the transaction. The Gemara suggests: Let us say that the mishna supports his opinion, as the merchants of Lod reverted to following the statement of the Rabbis. Granted, if you say that a seller may always renege on a transaction,

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

Bava Metzia 50b examines Rabbi Tarfon's view on price discrepancy thresholds and how long a buyer can rescind an overpriced sale.