Explanation #1 (Rashbam): [There is no difference between] the wheat, and its value, e.g. wine, if he has.

Explanation: He permits only wine, but not coins.

Rebuttal (R. Tam) Citation (Bava Kama 103a): Rav Kahana bought flax. The price went up, and the original owner sold it to someone else [and stipulated that the buyer will pay Rav Kahana];

Citation (cont.): Rav Kahana asked Rav whether or not he may take the money. Rav permitted only if the seller told the buyer 'this is Rav Kahana's flax'. This is like Rav taught, that one may not do Emanah with money.

Inference: R. Yanai (who argues with Rav) permits taking the money [in any case]!

Assertion: Even if the seller ate [the wheat on which Meshichah was done], he may pay different wheat if the price will rise.

Question: Why is this unless Se'ah b'Se'ah, which is forbidden (62a, lest the price rise, and he returns Peros worth more)?

Answer: There it is a loan, and here it is a sale;

Here, Meshichah is only to permit contracting, but not to truly acquire.

Explanation: Even though at the time of payment it is Ribis, since at the time of the contract there is one side (possibility) of Heter, it is permitted.

Question: If so, R. Yehudah should permit lending also Se'ah b'Se'ah, for it is Tzad Echad. Perhaps the price will not rise!

R. Yehudah permits Tzad Echad b'Ribis also in a loan, like we say below (65b) regarding one who gave a house or field for collateral "this is unlike R. Yehudah"!

Answer: He considers Tzad Echad b'Ribis only something that is in the lender's or borrower's ability to do in one way that there will not be Ribis;

This is unlike Se'ah b'Se'ah, which depends on the market price. Against his will it will be Ribis if the price rises.

Question: Why do Rabanan forbid? What Ribis is this? When he comes to redeem, first he will deduct [the value of] the Peros that he ate!

Answer: Surely if he does so it is not Ribis. Rather, the lender forces him to pay everything before he deducts anything, and if he cannot pay him everything, [the collateral] will remain in his hand.

Question - Citation (Erchin 31a - Mishnah): One who sells a Bayis Ir Chomah (a house in a walled city) may redeem it immediately, or until 12 months. This is like Ribis (the buyer lived in it without paying rent, because the seller had his money), and it is not Ribis.

Citation (cont.) Contradiction (Beraisa): It is absolute Ribis, but the Torah permitted it.

Citation (cont.) Answer: This (the Beraisa) is R. Yehudah, and this (the Mishnah) is Rabanan.

Summation of question: According to Rava, all forbid Tzad Echad b'Ribis. What was the answer?!

Answer: Mid'Oraisa, Rava agrees that [R. Yehudah and Rabanan] argue about Tzad Echad b'Ribis. However, mid'Rabanan, Rava holds that no one permits;

Here, R. Yehudah permits even mid'Rabanan, like is proven from the episode brought. Therefore, Rava establishes it to discuss Ribis on condition to return it.

Question - Citation (Megilah 27b - Beraisa - R. Meir): We sell a Beis ha'Keneses only on condition that when [the seller] wants, it will return.

Citation (cont.): According to R. Meir, how may [the buyer] live in it? This is Ribis! He holds like R. Yehudah, who permits Tzad Echad b'Ribis.

Answer: According to Rava, there it discusses that he stipulated with him that if they will redeem, [the buyer] will pay rental for having lived in it.

Question (Rashi): Our Mishnah teaches this! When there is a market price, one may contract!

Answer (Rashi): There is an opinion that one may not contract based on a market price. He establishes the Mishnah to be when storehouses [are open] and ships [arrive with grain].

Objection: [Rashi] should not explain like this. Even according to R. Yochanan, who says below that one may not contract based on a market price, does not require a price that will last so long as in a case of storehouses and ships. He requires only a great market;

R. Yochanan said that one may not contract, i.e. only regarding a market price of [medium size] cities.

Question: How do we learn from R. Yanai that one may contract based on a market of cities, and we do not require a great market?

Answer: We infer as follows. Since R. Yanai said "what is the difference between them and their money?", and he can pay money just like he can pay wheat, for from the wheat he can obtain money;

Similarly, we contract even based on a market of cities, for it is easier for one who has money to buy wheat even in a market of cities than for one who has wheat to sell, even in a market of storehouses and ships.

Explanation: [If] at time Ploni they are around, it is permitted. If they are not around, it is forbidden;

However, one may contract four for a Zuz, since this is the price, for one may contract for the market price.

Question: Why is it forbidden to contract five for a Zuz? Why is this unlike Tarsha?

Rav Nachman himself said below (65a) that Tarsha is permitted, to sell merchandise with a delay [before the buyer will pay] for more than its value, as long as he does not specify that if [he pays] now, the price is less!

Answer: Since here they sell for four for a Zuz, it is as if he specified that if [he pays] now, the price is less, and if he pays later, it is more.

Consequence: According to this, Rav Nachman permits Tarsha only in a matter whose appraisal is not known, e.g. a cow or Talis;

However, Peros, if there is a market price, Tarsha is forbidden with them.

Question: Rav Nachman rules below (75a) like Hillel, who forbids "until my son will come"!

Answer: Surely, in the way of a loan it is forbidden, even Se'ah b'Se'ah. However, in the way of a sale, like here, it is permitted, even [the value of] five for four.

Proof: If not, one could ask that even Rabanan below permit only Se'ah b'Se'ah, but not a Se'ah for two Sa'im!

Rather, it is like I explained. In the way of a sale, even five for four, it is permitted more than in the way of a loan, even Se'ah b'Se'ah, for here all permit.

Question: It would have been more proper to bring here that one may contract on a stack, which resembles a sale more!

Answer: Contracting on a stack, we permit only to contract with him for the price of gatherers, but not to contract what is worth six for five, since he does not have yet, for they still need fixing;

If he [sells] so much cheaper, it looks like Ribis.

However, when he has ready prepared [merchandise], just he lacks his son's arrival or bringing the key [before he can give it], even the value of five for four is permitted.

It means as follows. It is like "until my son will come", and here [regarding a sale] all permit, like Rabanan permit there.