Inference: Rav Nachman does not argue with his Rebbi, Rav Chasa.

Question (R. Tam): Below (108a), we say that if one sold for 200 and it was worth 100, we thought to say [that the neighbor, who has first rights to buy, can tell the buyer 'you were like a Shali'ach to buy the land for me, but not to overpay! I need to pay you only 100]. Rav Nachman said that there is no Ona'ah in land;

Inference: Even Bitul Mekach does not apply to land!

Answer (R. Tam): There is no Ona'ah until half (the land is worth only half the price, or the price is only half the value of the land), but from a half and onwards (it is less than a half), it is called Bitul Mekach, and [land] has [Ona'ah].

Support #1: In the Mishnah above (56b), R. Yehudah says that even one who sells an animal or pearl, there is no Ona'ah, and the Gemara explains, this is until their value;

Inference: Since he said "even", this connotes that the same Shi'ur applies to land.

Support #1: A Mishnah in Kesuvos (99b) says that if judges appraised land for a sixth too little or a sixth too much, their sale is Batel. R. Shimon ben Gamliel says, their sale is valid;

The Gemara explains that their sale is valid until a half.

Explanation: According to the opinion that mid'Rabanan, he must compensate [Hekdesh for what the Korban was worth more than what he redeemed it on), it totally became Chulin, just mid'Rabanan, one must pay Hekdesh the Ona'ah;

According to the opinion that mid'Oraisa he must compensate, Bitul Mekach applies to Hekdesh. An amount corresponding to the coins that he gave becomes Chulin, and the rest becomes Chulin through the [additional] money that he pays.

This teaches that we do not say that since Bitul Mekach applies to Hekdesh, the Pidyon is Batel and nothing became Chulin, similar to a person, in which the sale is Batel;

Explanation: The reason is because regarding a person, the afflicter can retract because he does not want to return the Ona'ah;

Even if the afflicted party exempts him from returning the Ona'ah, in any case both can retract, because the afflicted party could have come to a loss, if he would not realize and retract within the time to show [the Mekach to a merchant or relative];

However, [regarding] Hekdesh, the afflicted party cannot come to a loss. When the redeemer knows that he afflicted Hekdesh, he one may not benefit from it until he adds to his money until [in all, he gave] its value;

Therefore, he must add, and he cannot retract.

Even one who mistakenly obligates himself to Hekdesh, he loses, like we say in Bava Basra (133b, regarding one who wanted to sell a pearl to Hekdesh) "do not appraise it yourself, for what one says to Hekdesh is [a Kinyan,] like Mesirah to a person";

All the more so here, he is obligated to add, even though he erred, and he thought that through this (what he gave to redeem it) the entire Hekdesh will be redeemed, and he will not need to add;

This is because in any case he wanted to redeem for the value. Presumably, he did not intend to afflict Hekdesh, and he cannot retract. Therefore, both of them cannot retract.

Explanation: [He said that] Bitul Mekach applies [to Hekdesh. I.e., one must add until he pays the full value of what he redeemed.]

Implied question: Why couldn't we answer that [R. Yochanan taught that mid'Oraisa it is redeemed, but] Bitul Mekach applies mid'Rabanan?

Answer: If so, what is the difference between Ona'ah of Hekdesh and Bitul Mekach? Also regarding Ona'ah, one must add money [until he gives the full value] mid'Rabanan!

Source #1: We asked "if [the error was a sixth, i.e. the Shi'ur of] Ona'ah, would Reish Lakish say in such a case that mid'Oraisa [he must compensate Hekdesh]?!" However, according to R. Yochanan, who said that mid'Rabanan [he must compensate Hekdesh] this was fine. (This shows that returning the Ona'ah is mid'Rabanan.)

Source #2: Also above (in a Beraisa on 55a, if one said 'this cow or garment is in place of this Hekdesh cow', it is redeemed, and) it says that Hekdesh has the upper hand, even regarding [an error the Shi'ur of] Ona'ah.

Note: Tosfos understands "it is redeemed" to mean totally. Therefore, we must say that he must add money only mid'Rabanan. However, the Rosh (in Shitah Mekubetzes) says that "it is redeemed" according to what he gave, and he must add mid'Oraisa.

Source #3: If the Bitul Mekach that R. Yonah said is mid'Rabanan, if so we must say that according to the opinion that there is no Bitul Mekach, even mid'Rabanan he need not pay money;

[The Mishnah] explicitly teaches that he must compensate, and above it says that Hekdesh has the upper hand!

Question #1: In Erchin (29a), it says "Shmuel said that he redeemed it. Did he say l'Chatchilah?!"

Question #2: In Sanhedrin (14b), it says that regarding the appraisal of Hekdesh, we require nine and a Kohen, and the owner is always first to redeem, for he adds a Chomesh. This shows that we seek that Hekdesh profit!

Answer: It means as follows. Shmuel said when he redeemed it, i.e. he intended to redeem it for less than its value. This is forbidden to do, and he must complete [the rest of the value] only mid'Rabanan;

However, l'Chatchilah, that he did something permitted, that he intended to redeem it for its value, and he erred, and it turns out Hekdesh is worth more, mid'Oraisa he must complete!

Explanation: The other opinion says that even l'Chatchilah, he needs to complete only mid'Rabanan, even though he intended to redeem it for its value;

However, all forbid to afflict Hekdesh b'Mezid!

Explanation: This is only regarding Hekdesh. [An error about] land does not return, until half.

Explanation: This is a Chidush that a person is more stringent;

However, regarding Hekdesh, is this the stringency?! I.e. what is the Chidush that we find a stringency in Hekdesh over a person?

Assertion: The text does not say "Tu Lo" (and nothing else), for even regarding a person, there are more [stringencies]. A Shomer Chinam does not swear [about Hekdesh], and all these of our Mishnah (56a).

Implied question: Why can't say that he lent to him b'Mezid, so it did not become Chulin? (Me'ilah does not apply b'Mezid.)

Answer: If so, there is no Ribis, since the borrower may not use the money, and he did not acquire it.

Question: What is the case?

If there is a market price, or there is no market price and he has (flour), also for a person it is permitted!

If there is no market price, and additionally he has no (flour), on what does he redeem Hekdesh coins?

Suggestion: He redeems on a Perutah. [We permit this, because] Hekdesh will profit, for he stipulates to give to Hekdesh four Sa'im for a Sela for the entire year!

Rejection: Since at the time of Chilul, he redeems on something that is not worth [the Hekdesh], this is a disgrace.

Proof: If you would not say so, why did we retract from establishing that he lent 100 [for 120]?

Note: We retracted because the Gizbar transgressed Me'ilah, and it is like a loan to a person. Tosfos infers that if we could redeem on a Perutah, because Hekdesh will profit, why did we say Stam that the Gizbar transgressed Me'ilah? Perhaps he redeemed on a Perutah!

Suggestion: Lev Beis Din stipulates that it be redeemed, in order that Hekdesh will profit.

Rejection: If so, why did we retract from the first answer (he lent 100 for 120)?

Answer: The case is, a person volunteered to give 100 Sela'im, but he was not Makdish them yet. He gave them to a baker, in order to give to Hekdesh four Sa'im for each Sela. There was a market price of [early] gatherers;

However, if there was no market price at all, it is forbidden, lest he come to be confused with a person (and people will stipulate like this without a market price, which is forbidden). Therefore, it discusses that afterwards the price was three [Sa'im for a Sela].

Similarly regarding coins. If he gave 100 Zuz to a man to return to Hekdesh 120, it is forbidden. It seems that it is forbidden even mid'Oraisa, for it is considered as if he receives from the borrower himself;

Source: This is like (Kidushin 7a) "give 100 to Ploni, and I will be Mekudeshes to you." She is Mekudeshes based on the law of Arev (a guarantor. When the lender gives to the borrower, the Arev is obligated, as if he received.) It is as if she received from him.

Implied question: Below, we permit lending 100 rocks for 120!

Answer: The Gizbar himself gives them, and they are rocks. It is evident that they are of Hekdesh;

However, in the way of a sale, that he gave for flour, and there was a market price of gatherers, it is permitted to Hekdesh. (Maharsha - above, Tosfos required two indications that they are of Hekdesh, for it is a loan.)

Assertion: Similarly, [a Shomer Chinam for Hekdesh] does not pay;

Even a Shomer Sachar who was negligent, it seems that he does not pay, since we ask below (58a) from one who hired a worker to guard [for Hekdesh. If he is not paid for the week, he is responsible for Shabbos]. We did not answer that [he is liable when] he was negligent!

Explanation: This is because he was totally excluded from the Parshah [of Shemirah].

Question: Why didn't it teach that he does not pay? This is a bigger Chidush!

Answer: [This Mishnah] is primarily in Shevuos (42b, regarding Shevu'ah). It was brought here due to there.

Observation: In Bava Kama (76a) we exclude this from "v'Gunav mi'Beis ha'Ish."

Question: In Nazir (35a) we expound a Klal u'Ferat u'Chlal, and in Toras Kohanim we expound just a Klal u'Ferat!

Answer: All of these Kelalim and Peratim are an Asmachta, for in Bava Kama (64b) we expound "Al Shor, Chamor and Seh" [through the method of Ribuy u'Mi'ut]. One excludes land, one excludes slaves, and one excludes documents, both from Kefel and Shevu'ah;

Support: Now it is fine that in Shevuos (39b) we expound "Kesef Oh Kelim" - just like Kelim connotes two, also Kesef is two. Just like Kesef is an important matter... (That is a real Drashah. The Klal u'Ferat u'Chlal here is an Asmachta.)