OPINIONS: The Gemara quotes Rava who rules that when one sells merchandise based on measurement, weight, or an item-count, he must give the buyer the exact measure, weight, or count agreed upon; if he gives any less, the Halachah of Ona'ah applies and the buyer can retract the entire sale. Cheating the buyer with measures differs from cheating the buyer in the price of the merchandise, in which case the buyer may not retract the sale unless he was overcharged more than a sixth of the market value of the item. If he was overcharged less than a sixth, he may not even claim the money which he was cheated. (The ROSH is in doubt about whether there is even a prohibition against overcharging such an amount.) This is not the law in the case of measures, weights, and item-counts.

Does this mean that if a seller agrees to sell, for example, 100 nails, and the bag that he gives to the buyer contains only 99 nails, that the buyer may retract the entire sale and the seller does not have the opportunity to give the buyer one more nail?

(a) The RAMBAM (Hilchos Mechirah 15:2), according to the RAN's understanding, maintains that Rava's ruling is not absolute. Rava agrees that there are situations in which the sale is not invalidated, such as a sale which can be adjusted easily. In such a case, the sale is not considered to have been completed until the count of goods is corrected. Rava's ruling applies in a case in which the measure or count delivered is not rectifiable, such as when a person agrees to sell a house of 100 square meters, but the house actually measures only 70 square meters. Since one cannot simply add more space to a house, the sale is invalidated. This is also the opinion of the RAMBAN and most Rishonim.

(b) The RASHBA in Kidushin (42b) maintains that Rava's ruling is absolute; it applies whether the person was overcharged less than a sixth, exactly a sixth, or more than a sixth. However, he points out that Rava does not say that the sale is "Batel" -- "invalid," but rather that it is "Chozer" -- "returns." The Rashba explains that Rava means sales of an inaccurate measure, weight, or item-count are never invalidated, but rather the difference between the amount delivered and the specified amount must be compensated, whether in units or in price. According to the Rashba, there is no actual difference between the case of the house and the nails. In both cases, the sale is valid, and the amount must be compensated either by supplying the difference in quantity (as in the case of the nails) or by supplying the difference in money (as in the case of the house).

The PISCHEI CHOSHEN (Ona'ah 11:24, see footnotes there) quotes the S'MA who rules like the Rambam, Ramban, and other Rishonim. However, if a person is able to add more space to a house and thereby abide by his agreement with the buyer to give the buyer a 100-meter house, the S'ma presumably would agree this is permitted and the buyer cannot back out of the sale. This is implied by his statement that if a person sells a field which contains less area than he originally stated, the sale is upheld if he can add area from land located at the side of the field he sold. He may not add the additional area from land in another location. (Y. MONTROSE)

The Gemara teaches that the verse, "So has Hash-m sworn, by the glory of Yakov, 'I will never forget, for eternity, all of their deeds'" (Amos 8:7), refers to four types of people: "Otzrei Peiros" -- those who hoard produce (refraining from selling it until the demand is so great that they can raise the prices significantly), "Melavei b'Ribis" -- those who lend with interest, "Maktinei Eifah" -- those who decrease the size of their Eifah measure (in order to cheat the buyers), and "Mafki'ei She'arim" -- those who add to the market price (by withholding the produce until the end of the month; see RASHBAM DH Masai Ya'avor, and see TORAS CHAIM who disagrees with the explanation of the Rashbam).

The Gemara gives an example of a notorious "Otzar Peiros." He was so entrenched in such conduct that he received the appellation, "Shabsai Otzar Peiros."

The Gemara in Yoma (82b-83a; see Insights to Yoma 82:1) relates that there were two pregnant women who smelled food on Yom Kippur and had a strong urge to eat. Rebbi Chanina advised that the people whisper in their ears that it is Yom Kippur in order to calm down the urge of each fetus. One woman's urge diminished and she did not eat. She eventually gave birth to a child who became the great Rebbi Yochanan. They applied to him the verse, "Before I formed you in the womb I knew you" (Yirmeyahu 1:5).

The fetus of the other woman, however, did not accept the censure, and its urge persisted. They applied to the baby the verse, "The wicked are estranged from the womb" (Tehilim 58:4). The baby grew up to be Shabsai, the one who hoarded produce to raise the prices.

Many commentaries, including the VILNA GA'ON, explain that the beginnings of these two lives, that of the Tzadik, Rebbi Yochanan, and that of the Rasha, Shabsai, are hinted to in the verse at the end of Parshas Shemini: "To distinguish between the impure (Tamei) and the pure (Tahor), and between the creature (Chayah) that may be eaten and the creature (Chayah) that may not be eaten" (Vayikra 11:47).

The Vilna Ga'on explains that the verse may also refer to what separates a person who is inclined to be a Rasha and a person who is inclined to be a Tzadik, as the Gemara in Yoma indicates. The word "Chayah" ("animal") is also the word used for a woman who is in the process of giving birth. The verse alludes to the difference between the Rasha and the Tzadik by distinguishing between the "woman who ate" and "the woman who did not eat." The Vilna Ga'on explains this verse homiletically to mean, "In order to distinguish between the Tamei (the wicked person) and the Tahor (the righteous person), one can observe which Chayah (pregnant woman) eats [on Yom Kippur when the fetus craves food] and which Chayah does not eat." This Derashah is supported by the fact that the very next Parshah (Tazria) discusses the laws of a woman who gives birth to a son. (Y. MONTROSE)