We continue in Bava Metzia, chapter 4, Mishnah 4. This Mishnah continues from the previous one and opens with the word "Keitzad" - meaning, it comes to give a practical example of the principle that was explained.
The two cases in the Mishnah:
The buyer took the produce and has not yet paid - he cannot back out of the transaction. As explained, taking the merchandise is what effects the acquisition; once he has pulled the merchandise, it becomes his, and all that remains is for him to pay its monetary value.
The buyer gave the money and has not yet taken the merchandise - he can back out, since the transaction was not completed. The acquisition is effected only through pulling the merchandise, and paying the money does not close the transaction. Therefore both parties are permitted to back out and say they found a better deal elsewhere, and this is their legal right.
The dispute among the Amoraim regarding acquisition through money:
In the Gemara they dispute whether giving money alone constitutes an act of acquisition: according to Rabbi Yochanan, by Torah law money acquires; according to Reish Lakish, money does not acquire. Our Mishnah takes the position that money does not acquire, and Rabbi Yochanan explains that the reason for this is not by Torah law but rather by rabbinic enactment.
Why did the Sages see fit to enact this? They were concerned that once the money reaches the hands of the seller, he will no longer take responsibility for the merchandise. For if the merchandise is still sitting in his warehouse and a fire breaks out, he would just pick up the phone and say to the buyer: "You better hurry, otherwise your property will burn." And since he is not protecting the merchandise, he is not protecting the buyer from loss, since it is no longer his problem - he has already sold it. While this is not moral behavior, from a halachic perspective he would have the right to do so. Therefore the Sages enacted that as long as the buyer has not come into physical possession of the merchandise - through lifting, pulling or the like - the transfer of ownership is not complete, and the transaction is not finished.
The halachah emerges that by Torah law, handing over the money does indeed effect an acquisition, whereas by rabbinic law it does not acquire.
The Mishnah continues: "Aval amru" - meaning, the Sages said. Once the money is handed over, even though technically one can back out of the transaction by virtue of a rabbinic enactment, the Rishonim dispute what exactly the Sages effected: Did they establish that the acquisition does not take effect at all, or that the acquisition takes effect and nevertheless one is permitted to back out. Either way, the point is that strictly according to the law the buyer can back out and take his money back.
For example: A person wants to buy a used car, and the seller offers him a red Toyota of a certain year for ten thousand dollars. The buyer agrees and gives him a down payment, or the full amount (and even on this there is a dispute, but this is not the place for it). Before he comes to take the car, he discovers that another person is selling an identical car for nine thousand. He goes back to the seller and says: "I am not interested, return my money. I have not taken the car and there is no binding acquisition here, since I found a better deal." A person is permitted to do so according to the law, but one who does this is a bad person, who is not decent and does not stand by his word.
The law of "Mi Shepara":
Furthermore, the Sages established a sort of curse against him, and according to Rava - and this is the halachah - they actually curse him in the rabbinic court. This curse is called the law of "Mi Shepara", meaning He who exacted retribution and settled accounts and paid them their due. The language of the Mishnah: "Mi shepara meanshei dor hamabul umidor haplagah" - He who exacted retribution from the people of the generation of the Flood in the days of Noach, and from the generation of the Dispersion, which is the generation of the Tower of Bavel after Noach, who received their punishment. The Bartenura brings a text matching the language of the Baraisa in the Gemara, that this does not only apply to these two, but also "ume'anshei Sedom" - the people of Sodom and Gomorrah, "umimizrayim sheshetafam bayam" - the Egyptians whom Hashem drowned in the sea.
And the Mishnah concludes: "Hu asid lipara mimi she'eino omed bediburo" - that same Hashem will settle accounts in a similar fashion with one who does not stand by his word, which is the person who paid money and backs out of the transaction. True, his money is returned to his hand, but he emerges a bad person; the Sages curse him, and it is a frightening curse: That same Hashem who exacted retribution from those people will exact retribution from him as well.
It is worth noting that the curse of "Mi shepara" applies only to someone who actually gave money. A person who gave his word alone and said, "I will take your car, and let us meet tomorrow to exchange the cash for the car," and the next day wishes to back out - he too is not keeping his word and the Sages are displeased with him. Nevertheless, the curse of "Mi shepara" does not apply to him, since he did not hand over the money.
The View of Rabbi Shimon:
The final opinion in the Mishnah, which is a bit difficult to understand, is the view of Rabbi Shimon. Rabbi Shimon follows the view of Rabbi Yochanan in the Gemara, that handing over money does indeed constitute an act of acquisition. However, the Sages intervened and established that money does not acquire - but they did so in a more limited manner. Therefore, Rabbi Shimon says: If the money passed from hand to hand, meaning that the buyer gave the money to the seller, the person holding the money - the seller - has the upper hand. This is not just a figure of speech, but a term indicating that the choice is in his hands: to return the money, or to say that the transaction is binding. However, from the perspective of the buyer, Rabbi Shimon holds that once he has handed over his money, he can no longer back out; there is no question of "Mi shepara" here at all, rather he is completely bound by the transaction.
Regarding the reasoning behind Rabbi Shimon's view, two approaches have been suggested, and this is a major dispute:
The Explanation of the Bartenura: The Bartenura, based on the Gemara, interprets Rabbi Shimon's words as referring to a specific case with limited application: when the merchant rents property from the buyer. How so? Reuven has a warehouse, and Shimon the merchant is looking for a place to store his wine; Reuven rents him a section of the warehouse, and Shimon places his wine in that spot. Eventually, Reuven needs wine, so he turns to Shimon and asks to buy some of his wine. They agree on a price, and Reuven hands over the money. In such a scenario, says Rabbi Shimon, handing over the cash is a closed deal from Reuven's perspective, even though Shimon can still back out.
And the reason: The only reason we sought to limit the validity of handing over money was so that the merchants would take responsibility for the merchandise, lest a fire break out. But here, if a fire breaks out in the warehouse - the warehouse belongs to Reuven, and it is in his power to take matters into his own hands and save his merchandise himself, so there is no room for concern regarding him. Consequently, only the seller's side remains, and regarding him we say: As long as he has the ability to back out of the transaction - that is sufficient.
The Explanation of Rashi: Tosafos is not comfortable with this simple reading, and prefers Rashi's approach, which is more general and does not depend specifically on the merchandise being located on the buyer's property. The basis of the matter is as follows: Once we have given the seller the right to back out of the transaction if he wishes, he has a basic financial incentive to keep his options open, like a free call option. He says to himself: If the market changes and I can get a higher price for my wine, I will return the cash. The very possibility that he might profit will cause him to be meticulous and guard the merchandise even after he has taken the money, in case a better deal comes along. And if a fire breaks out, he will say: I had better save the merchandise, because a fire spreading through the city will reduce the supply of wine, and I will be able to get a higher price. It turns out that he will take responsibility for the merchandise, and therefore Rabbi Shimon says: Since he has the ability to back out, he will guard it, and there is no reason not to consider the transaction binding by virtue of the buyer handing over the money.
The Halachah: As difficult as this plain meaning is, the halachah does not follow Rabbi Shimon, but rather the Tanna Kamma, and as we have said all along: Taking the merchandise is what finalizes the acquisition, and handing over money never acquires. However, from the moment the money is handed over, one who backs out is liable to incur the curse of "Mi shepara".