1) THE CASE OF THE RULE OF RAV AND SHMUEL
OPINIONS: Rav and Shmuel state a rule about business deals: If a buyer and seller agree on the sale of a Kor (thirty Se'ah) of grain "for thirty Sela," the buyer may retract the sale even while he handles the last Se'ah of produce. In contrast, if they agree on the sale of a Kor of grain but they stipulate that the price is "one Sela per Se'ah," each Se'ah of grain is considered an independent sale and is acquired separately. In exactly what case does this rule apply?
(a) The RIF explains that this rule applies in the case of a transaction conducted in a Simta (as opposed to Reshus ha'Rabim, the public domain), or in the domain of the buyer with the vessels of the seller. The Rif explains that if the transaction was conducted either in Reshus ha'Rabim or in the domain of the seller, the Halachah is that the vessels of the buyer cannot acquire on his behalf in Reshus ha'Rabim or in the domain of the seller. If the sale was conducted in the domain of the buyer and the transfer of goods was not done in the vessels of the seller, once the seller and buyer agree to an amount the domain of the buyer automatically acquires the goods on his behalf. It is clear that Rav and Shmuel refer to a transfer of goods that takes time. This is why the deal must be either in a Simta or in the domain of the buyer with the vessels of the seller. Rav and Shmuel are teaching that the grain is measured out gradually. If the deal involves the sale of a Kor, then the transaction is not complete until the last Se'ah is measured. However, if the payment is per Se'ah, then each Se'ah that is measured out is automatically transferred to the ownership of the buyer.
(b) The BA'AL HA'ME'OR argues that the transaction also could take place in the property of the buyer without the vessels of the seller. Although one might assume, as the Rif indeed writes, that the buyer's domain should acquire the grain immediately, his domain acquires immediately only in a case in which no specific amount is mentioned (but rather they agree on the sale of "all of the grain in this barrel"). When a specific amount is mentioned, the transaction is not considered complete until the entire specified amount is weighed out.
2) HALACHAH: AN EXCEPTION TO THE RULE OF RAV AND SHMUEL
QUESTION: Rav and Shmuel state a rule about business deals: If a buyer and seller agree on the sale of a Kor (thirty Se'ah) of grain "for thirty Sela," the buyer may retract the sale even while he handles the last Se'ah of produce. In contrast, if they agree on the sale of a Kor of grain but they stipulate that the price is "one Sela per Se'ah," each Se'ah of grain is considered an independent sale and is acquired separately. (See previous Insight.)
Does Rav and Shmuel's rule have any common exceptions?
ANSWER: The PISCHEI TESHUVAH (YD 200:7) quotes the KESONES PASIM who was asked to judge a case which clearly was one to which Rav and Shmuel's rule applied. Two people agreed upon the sale of oxen. They agreed that twenty oxen would be sold to the buyer at a fixed price per ox. The buyer began to do Meshichah to each ox in order to make a Kinyan. In the middle of the buyer's ox-pulling, the seller decided that he did not want to go through with the sale. Who owns the oxen to which the buyer already did Meshichah? This apparently is a classic application of the rule of Rav and Shmuel, that when a Kor of grain is sold at the price of one Sela per Se'ah, the buyer acquires each Se'ah of grain that he lifts up, and the seller cannot retract the sale of those Se'ah. He may renege only on the sale of the grain on which the buyer has not yet made a Kinyan.
The Kesones Pasim, however, ruled that the seller may renege on the sale of all of the oxen. He explained that the Halachah of Rav and Shmuel applies only when there is a real price for every Se'ah of grain. This means that each Se'ah of grain indeed was worth a Sela. However, in the case of a large cattle deal, although the parties agreed on a set price per head of, each individual ox is actually worth a different amount of money. The price per head agreement was only a way to express the price for the group; it did not represent the actual value of each animal. Therefore, the Kesones Pasim ruled that despite the agreement of a set price per head, the price in this case is judged as one lump sum. (Y. MONTROSE)