Related for Bava Metzia 4:3
הָאוֹנָאָה, אַרְבָּעָה כֶסֶף מֵעֶשְׂרִים וְאַרְבָּעָה כֶסֶף לַסֶּלַע, שְׁתוּת לַמִּקָּח. עַד מָתַי מֻתָּר לְהַחֲזִיר. עַד כְּדֵי שֶׁיַּרְאֶה לְתַגָּר אוֹ לִקְרוֹבוֹ. הוֹרָה רַבִּי טַרְפוֹן בְּלוֹד, הָאוֹנָאָה שְׁמֹנָה כֶסֶף לַסֶּלַע, שְׁלִישׁ לַמִּקָּח, וְשָׂמְחוּ תַגָּרֵי לוֹד. אָמַר לָהֶם, כָּל הַיּוֹם מֻתָּר לְהַחֲזִיר. אָמְרוּ לוֹ, יַנִּיחַ לָנוּ רַבִּי טַרְפוֹן בִּמְקוֹמֵנוּ, וְחָזְרוּ לְדִבְרֵי חֲכָמִים:
Ona'ah ("Wronging") is four [ma'ah of] silver [of six ma'ah to a dinar, a sela being four dinars], of twenty-four [ma'ah] of silver to a sela, a sixth of the purchase. [If the purchase were for a sela, twenty-four ma'ah (of silver), ona'ah being one-sixth of the purchase, he must return the entire ona'ah, four (ma'ah of) silver.] Until when is he [who was wronged] permitted to retract? ["permitted" is stated to apprise us that even "He who exacted payment, etc." does not obtain if the purchase were retracted or the sixth returned.] Until he can show it [the purchase] to a merchant or to one of his kin. [And if he took longer, he (is regarded as having) waived his ona'ah. And the seller can always retract. For the purchase is not in his hand for him to show it to a merchant or to his kin if he were wronged. And if it were known that there had come to his hand a similar purchase, and he knew that he had erred, and he kept quiet and made no claim, he cannot go back and claim, having pardoned.] R. Tarfon taught in Lod: Ona'ah is eight (ma'ah of) silver to a sela, a third of the purchase — and the merchants of Lod rejoiced. [For they were expert in wares and they sold them dear. The halachah is not in accordance with R. Tarfon.] He said to them: "It is permitted to retract the entire day" — at which they said: "Let R. Tarfon leave us in our place" — and they reverted to the words of the sages.