Gemara

(Rav Chisda): If one damages or eats Matanos Kehunah (things that must be given to Kohanim), he is exempt.

Question: What is his reason?

Answer #1: He learns from "v'Zeh Yihyeh Mishpat ha'Kohanim." (Matanos Kehunah themselves are given, but not compensation for damaging them.)

Answer #2: It is Mamon she'Ein Lo Tov'im (no one can claim compensation. The damager can say 'I will pay a different Kohen.')

Question (Beraisa - R. Yehudah ben Beseira): "Mishpat" teaches that Beis Din enforces the Matanos, i.e. they force a damager to pay.

Answer: The case is, he received the animal before the Matanos were separated. The Tana teaches that Matanos are considered separated (and the Kohen acquired them) even before they are separated.

Question (Mishnah - R. Eliezer): If a rich person away from home has no money, he may take Matanos Aniyim (Leket, Shichechah and Pe'ah, which are left for the poor). When he gets home, he must pay.

Chachamim say, when he gets home he is exempt, for he was poor at the time.

Inference: Had he been rich at the time, he would be liable!

Answer (Rav Chisda): This is Midas Chasidus.

131a Question (Beraisa): If the king's officers took Reuven's grain for money that he owed, he must take Ma'aser (from other Tevel).

Answer: That case is different, for he saves money.

Question (Mishnah): If Reuven bought the innards of a cow from a butcher, Reuven gives the stomach to a Kohen, without deducting from the price;

If Reuven bought by weight, he gives the stomach to a Kohen, and does not pay for its weight.

Why must he give to a Kohen? Selling it is like damaging it. We should say that there is no longer a Mitzvah to give it!

Answer: When the Matanos are intact, they must be given.

A certain Levi used to seize Matanos (being sent to a Kohen).

Rav: Is it not enough that we do not make him give, that he even grabs from others?!

135a (Mishnah): If one dyed the wool before giving Reishis ha'Gez, he is exempt.

Rishonim

Rambam (Hilchos Bikurim 9:14): If a Yisrael transgressed and ate or damaged or sold Matanos Kehunah, he need not pay, for there is no known claimant. Even though one may not buy them, if he did, he may eat them, for Matanos Kehunah can be stolen.

Rambam (15): If Reuven told a butcher 'sell to me the innards of this cow', Reuven gives the stomach to a Kohen, without deducting from the price. If Reuven bought by weight, he gives the stomach to a Kohen, and deducts from what he pays to the butcher.

Ran (45b DH Lakach): He holds that Reuven is liable only when he weighed the meat himself. If he did not, he may eat them, for the butcher is the thief. Reuven may eat them, because Matanos Kehunah can be stolen (so Reuven acquired them).

Rosh (10:2): One opinion exempts one who damaged Matanos Kehunah from "Zeh". One opinion exempts because it is Mamon she'Ein Lo Tov'im. The first opinion exempts even b'Yedei Shamayim, for the Torah exempted him. According to the second opinion he is liable, just the Kohanim cannot force him to pay, for he can say 'I will pay another Kohen.' The Beraisa of R. Yehudah ben Beseirah expounds Zeh differently. This supports the second opinion. The Halachah follows the second opinion, to be stringent.

Rosh (11:2): If one dyed the wool before giving it, he is exempt. Since he intended to steal it from the Kohen and changed it, he acquired it. It is as if does not exist. This is like one who damaged or ate Matanos Kehunah. He is exempt.

Ran (44b DH v'Iy): If he is exempt because it is Mamon she'Ein Lo Tov'im, he should be exempt even if they are intact! It seems that the Gemara as follows. Since it is it is Mamon she'Ein Lo Tov'im, even though if they are intact he must give them (for it is a Mitzvah), when they are not intact, there is no Mitzvah and no law to pay money. Therefore, he is totally exempt, even to be Yotzei Yedei Shamayim. Tosfos says that the two versions argue about this. I disagree. The cases in the Gemara of Safek Mamon in which one is liable b'Yedei Shamayim (Bava Kama 103b, Bava Metzi'a 37a) are different. Here, if there is no Mitzvah, why is he liable?! However, according to both versions, it is Midas Chasidus to pay. The Gemara asked from one who ate Matanos Aniyim, which are also Mamon she'Ein Lo Tov'im. It answered that (if he were not an Oni at the time,) he would be liable due to Midas Chasidus. Do not say that the Gemara gave a second reason why he is exempt because there is a Nafka Minah (practical difference). Rather, it was not satisfied with the Drashah from "Zeh", for this word is needed for another Drashah.

Ran (ibid.): The Gemara asked from the case of officers who took Reuven's grain, and answered that there is different, for he saves money. Therefore, he must pay even though it is it is Mamon she'Ein Lo Tov'im, like a regular obligation to give Ma'aser. This teaches that even though the Halachah follows Rav Chisda, whenever he saves money in such a case, he is liable. Tosfos asked that one who ate Matanos Kehunah saved money, and answered that he could have fasted. I say that he is exempt even if he could not have fasted, for a Mishnah exempts one who dyed the wool before giving Reishis ha'Gez. He acquired through Shinuy; he is like one who damaged or ate Matanos Kehunah, therefore he is exempt. There, he surely saves money! Rather, if one intended to take Matanos Kehunah for himself and changed them through dying or eating, he does not pay even though he saves money. He uprooted the Mitzvah, and there is no Chiyuv Mamon (to pay money). When officers took his grain, he did not uproot the Mitzvah, and he saves money. The Mitzvah is still on him. Giving their value is like giving them. According to the opinion that Matanos are considered separated (and the Kohen acquired them) even before they are separated, if a Kohen received a full animal, he acquired the Matanos. If someone else ate them, he is liable. We hold like this, for we rule (Nedarim 85a) like the opinion that Tovas Hana'ah (the right to choose to whom to give Matanos) is considered Mamon (property). This is only if the Kohen received it slaughtered. When it was alive, there was no Chiyuv to give Matanos. It is like separating Chalah on flour. It is not Chalah, and it is theft if the Kohen takes it.

Rashba (132b DH Zos): Even though the Shochet slaughters for a Yisrael, he cannot tell the Kohen 'you have no claim against me. Go claim against the owner.' Rather, his claim is against the Shochet. The Shochet must give (the Matanos) to him. This does not mean that if the Shochet gave them to the owner or sold them, he is liable. We hold like Rav Chisda, that one who damages or eats Matanos Kehunah is exempt. The Shochet did not save money, for it is not his animal.

Tosfos (Bava Metzi'a 6b DH v'Ha): When a Kohen grabbed a Safek Bechor, why don't we take it from him? The owner can say 'I wanted to give it to another Kohen!' We can say that we discuss Makirei Kehunah (he always gives Matanos Kehunah to this Kohen). Alternatively, the owner can claim from the Kohen only the Tovas Hana'ah that he had in it, according to the opinion that Tovas Hana'ah is Mamon. In Chulin (131a), we say that the Levi who used to grab Matanos Kehunah acted indecently. This connotes that he need not pay. There is no proof from there. Perhaps he ate them; one who damaged or ate Matanos Kehunah is exempt.

Poskim

Shulchan Aruch (YD 61:15): If one did not give Matanos Kehunah, rather, he ate or destroyed them, Beis Din does not force him to pay, but he must pay their value to be Yotzei Yedei Shamayim.

Beis Yosef (DH veha'Rambam): It seems that the Rambam explains like Tosfos and the Rosh, and rules stringency like the second opinion. If not, why did he omit the verse? Also, Rav Chisda said 'exempt', and the Rambam changed this to say 'he is not liable', which connotes that Beis Din does not obligate him (but he is liable to be Yotzei Yedei Shamayim).

Taz (17): He is exempt because it is it is Mamon she'Ein Lo Tov'im, but if it is intact, Beis Din forces him to give, due to the Mitzvah to separate.

Chaguras Shmuel (on Levush, Ha'arah 30): The Rashba and Tosfos do not distinguish between the owner or others who damaged Matanos Kehunah.

Shulchan Aruch (31): If a Yisrael transgressed and ate the Matanos or sold them, he need not pay, for it is it is Mamon she'Ein Lo Tov'im.

Shach (19): He must pay in order to be Yotzei Yedei Shamayim, like we said above.

Pischei Teshuvah (13): The Shach (2) brought from the Ran that Matanos are considered separated, so if a full slaughtered animal came to a Kohen, he acquired the Matanos. Keneses ha'Gedolah (Hagahos Beis Yosef 19) says that since the Tur and Shulchan Aruch omitted this, they hold that Matanos that were not separated are not considered separated. Sha'ar ha'Melech (Hilchos Ishus 5:6) says that he overlooked the Tur and Shulchan Aruch in Hilchos inheritance, where they explicitly rule that they are considered separated. They say that a Bechor get a double share of Matanos that were not separated. It follows that one (who damaged them after a Kohen received the slaughtered animal) must pay.

Shulchan Aruch (ibid.): Even though one may not buy them, if he did, he may eat them, for Matanos Kehunah can be stolen.