Bava Metzia, Chapter 4, Mishnah 3. At the beginning of the chapter, it was noted that from here on, the tractate moves to the topic of commercial laws. The first two Mishnahs dealt with the details of acquisitions and money, and from here - from Mishnah 3 until the end of the chapter - the topic will be the laws of ona'ah.
What is 'Ona'ah'?
'Ona'ah' is a word that is difficult to translate. Some translate it as overcharging, deception, or fraud, and it seems that the closest translation is financial exploitation. The word is known mainly in the context of ona'as devarim - causing a person distress through words - whereas here the focus is financial ona'ah.
This prohibition is a Torah prohibition, as it is stated: "And if you sell a sale to your fellow, or buy from your fellow's hand, you shall not wrong one another" - whether selling merchandise to one's fellow or buying from him, it is forbidden for a person to deceive, exploit, and take advantage of his fellow by charging an exorbitant price. The difficulty in translation stems from the fact that the prohibition applies in both directions: not only overcharging the buyer, but also underpaying the seller. In both cases, there is an inherent exploitation of the other party by setting an unfair price.
Three levels of deviation from the fair price:
The task here is to define when a person has crossed the line and violated the Torah prohibition. There are three levels in this matter:
A minor deviation: Since it is impossible to determine the fair price exactly, and there are slight market fluctuations, the assumption is that people waive a small discrepancy, whether it is an overcharge or an underpayment. This is not ona'ah.
Exactly a shtut (a sixth): This is the measure of ona'ah. At this stage, the wronged party is entitled to demand the completion of the discrepancy, and according to the wording of this Mishnah, even to return the purchase.
More than a shtut: The wronged party - whether a buyer who was overcharged or a seller who received too little - may cancel the entire transaction, since it was not fair trade.
The measure of a shtut - an example:
If the fair price for a carton of eggs is twenty-four shekels, a sixth of it is four shekels. As long as the price is below twenty-eight shekels - it is within the permitted range. And similarly for the other side: a seller who is pressured to close the deal because he needs cash, and the buyer exploits his distress and says to him, "I will not pay twenty-four, but rather twenty-three, twenty-two, or twenty-one" - all of these are in the permitted range. But once he drops to twenty, he has deviated by four shekels, which is a sixth of the fair price, and this is ona'ah. The calculation is always made according to a sixth of the fair price.
The coin system in the Mishnah:
"Sela" - The largest coin in the system, which is worth four dinars.
"Dinar" (which is the zuz) - The most common and prevalent base coin, which contains six ma'ot.
"Ma'ah" - The smallest silver coin (and in the plural: ma'ot, which is also a general word for money).
It turns out that there are twenty-four ma'ot in one sela. Therefore, for an item whose fair price is a sela - twenty-four ma'ot - it is permitted to deviate by less than four ma'ot in either direction; once it deviates by four ma'ot in either direction, it has reached the measure of ona'ah.
In the words of the Mishnah: "Ha'ona'ah arba'ah kesef me'esrim ve'arba'ah kesef lasela - shetus lamikach" - the overcharge is four silver ma'ah coins out of the twenty-four silver coins in a sela, which is one-sixth of the purchase price.
"Ad masai mutar lehachzir" - Until when is one permitted to return it:
Once the deviation reaches this amount, the defrauded party is entitled - according to the wording of the Mishnah - to return the merchandise and say, "You charged me too much," or "You paid me too little." How much time is this window available to him? To this the Mishnah replies: "Ad kedei sheyar'eh latagar o likrovo" - the amount of time needed for him to show the item to a merchant, a professional who knows how to assess its true value, or to his relative. For example, if he bought a tray of eggs for twenty-eight shekels, and his wife says to him, "Their price is twenty-four, you paid one-sixth too much." At that time he is able to go back and return it; once the window closes, he can no longer do so. (According to halachah, he is not permitted to return the item for a one-sixth discrepancy, but rather to demand the difference, even though the wording of the Mishnah implies that he also has the ability to return it.)
The opinion of Rabbi Tarfon:
"Horah Rabbi Tarfon b'Lod: Ha'ona'ah shemonah kesef lasela - shelish lamikach" - Rabbi Tarfon disagrees with the Tanna Kamma, and although the halachah does not follow him, he established that the measure of overcharging is not one-sixth but one-third: eight silver coins out of twenty-four. According to him, for an item whose fair price is twenty-four, as long as the price does not reach thirty-two upwards or sixteen downwards, it remains within the permitted range; once it reaches these amounts, he has violated the prohibition of overcharging.
"Vesamchu tagarei Lod" - the merchants of Lod, who were apparently aggressive salespeople, rejoiced at this ruling, as it broadened their profit margin. Someone coming to buy a tray of eggs from them would hear, "For you, a special price - 31.90," and they would try their luck to get a much higher price than the fair market value.
"Amar lahem: Kol hayom mutar lehachzir" - Rabbi Tarfon said to them: Although I have been lenient with you regarding the profit margin, in return I have extended the time window. The defrauded party is allowed to return the item all day long and say, "I wish to cancel the transaction and get my money back" - and not just demand the return of the difference. It turns out that the built-in return policy in the system lasts a whole day.
"Amru lo: Nicha lan, Rabbi Tarfon, bimkomeinu" - the merchants answered him: Leave us to our custom. It is true that expanding the profit margin is an advantage, but the possibility of returns for a full day works to our detriment. The bottom line is that it is better for us to work with the previous method: not to charge more than one-sixth, but not to allow cancellation of the transaction beyond the short time it takes the buyer to go show the item to someone who understands its value, and return immediately.
"Vechazru divrei chachamim" - the merchants and markets in Lod went back to acting according to the words of the Sages: one-sixth constitutes overcharging, and the return window is just enough time to show the item to a merchant or relative and return immediately.
Halachah: The halachah is mostly in accordance with our Mishnah, except that at exactly one-sixth - unlike what is implied from the wording of the Mishnah - the defrauded party is not permitted to demand the cancellation of the entire transaction, but only the return of the difference to correct the overpayment or underpayment, and no more than that. At more than one-sixth, according to many poskim, the transaction can be cancelled completely, and by both sides of the transaction alike; except that the defrauding party cannot cancel it, so that a sinner should not be rewarded, while the defrauded party is permitted to cancel it unilaterally if he so desires.