OPINIONS: The Gemara discusses a case in which some time after performing Shechitah, the Shochet discovered a dent in the knife. When he examined the knife before Shechitah, he found no dents on it. Do we assume that the knife became blemished during the Shechitah and invalidate the Shechitah, or do we assume that it became blemished after the Shechitah? Rav Huna rules that the Shechitah is invalid, even if the Shochet had used the knife to cut bones after he used it for Shechitah. We assume, out of doubt, that the knife became blemished during the Shechitah, thereby tearing the Simanim instead of properly cutting them. Rav Chisda rules that the Shechitah is valid, since we assume that the dent in the knife came from the bones which were cut after the Shechitah.

According to Rav Huna, is the Shechitah invalid because a dent was found in the knife, or because the Shochet failed to examine the knife after Shechitah to determine that it had no dents? The difference between these two reasons is a case in which the knife became lost after the Shechitah, before the Shochet had a chance to examine it. According to the first reason, no dent was found on the knife, and thus we should assume that the Shechitah was valid. According to the second reason, it was not determined that the knife was perfectly smooth, and thus we must be concerned that perhaps it had a dent.

(a) The RAMBAN says that in a case in which the knife became lost before it was checked, Rav Huna would rule that the Shechitah is invalid. This is evident from the words of the Gemara here, which discusses the reasoning of each opinion. The Gemara says that Rav Huna's reasoning is clear; he follows his earlier teaching (9a) that an animal is considered prohibited until we know for certain that a valid Shechitah was performed. This implies that the knife must be checked after the Shechitah in order to determine that the animal was slaughtered properly, and without such an examination, the meat of that animal may not be eaten.

(b) RABEINU YONAH argues that Rav Huna would consider the animal to be properly slaughtered in a case in which the knife became lost after the Shechitah. When Rav Huna states earlier that such an animal is prohibited until we know for certain that a valid Shechitah was performed, he is referring only to a case in which the object had no Chezkas Kashrus (an acceptable assumption that the object is permitted), such as when the Simanim were not checked after the Shechitah, and thus we have no reason to assume that they were cut properly. The knife, which was examined before the Shechitah, has a Chezkas Kashrus until it is shown to be dented.

According to Rabeinu Yonah, when the Gemara explains Rav Huna's ruling here based on his statement earlier that an animal is forbidden until we know for certain that the Shechitah was performed properly, its intention is as follows. Without Rav Huna's previous statement, we would have thought that Rav Huna also rules that the Shechitah is valid, and we assume that the bones dented the knife after the Shechitah was performed. However, since Rav Huna says that an animal is forbidden in the case of any Shechitah that is not known to be definitely valid, the animal slaughtered with a knife that was later found to be dented cannot be deemed Kosher, since we do not know for certain that the knife was valid at the time of Shechitah, and it no longer has a Chezkas Kashrus. When, however, the knife was lost after the Shechitah before it was examined, there is no evidence to ruin the Chezkas Kashrus, and thus the Shechitah is assumed to be valid. This is also the opinion of the YAM SHEL SHLOMO (#18).

The SHITAH MEKUBETZES notes that RASHI seems to agree with the view of Rabeinu Yonah. This is apparent from Rashi's statement (in DH k'Shematei) that "this animal developed a Safek during the Shechitah," and that is why Rav Huna invalidates the Shechitah. Apparently, Rashi's intention is to explain that Rav Huna's statement applies only when a positive Safek occurs, and not when there never arose any reason to think that the knife was dented, such as a case where the knife became lost.

However, two other statements of Rashi imply that he agrees with the view of the Ramban. Rashi (DH ha'Shochet) states that the case of the Gemara is one in which the knife was not checked immediately after the Shechitah. This implies that we need to know for certain that there was no dent in order to validate the Shechitah. Similarly, Rashi (DH Afilu) says that even if bones were broken with the knife "between the Shechitah and the last examination of the knife," the Shechitah is invalid. This implies that it is necessary to check the knife after slaughtering, and we do not rely on a Chezkas Kashrus. (Perhaps Rashi means merely that one should check the knife, according to Rav Huna, but the lack of such an examination does not render the Shechitah invalid.) The Shitah Mekubetzes concludes that it is difficult to discern Rashi's opinion in this matter. (Y. MONTROSE)

QUESTION: Rava attempts to disprove the opinion of Rav Chisda from a Beraisa that states that when a person immerses himself in a Mikvah and afterwards finds an intervening substance on his body, his Tevilah is considered invalid. We assume that the substance was on his body during the Tevilah. Similarly, we should assume that the dent that was found on the knife after Shechitah was there during the Shechitah.

The Gemara rejects Rava's proof by pointing out that in the case of Tevilah, the validity of the person's Tevilah was compromised due to the substance that was found on his body afterwards. In contrast, in the case of the knife that was found to have a dent after the Shechitah, the validity of the knife was compromised, but not the Kosher-status of the animal.

The Gemara's logic is not clear. If the knife has a dent in it, then that should create a doubt in the Shechitah of the animal as well! A doubt about the validity of the knife should constitute a doubt about the validity of the Shechitah.

(a) RASHI (DH Behemah) implies that since the knife was used to cut bones after the Shechitah, the status of the knife can be dissociated from the status of the Shechitah of the animal. The animal can have a "Chezkas Shechutah," a Chazakah that it was slaughtered properly, and the nicked knife can be treated as a problem that arose after the animal had a "Chezkas Shechutah." In contrast, in the case of Tevilah, even though the person, after his immersion, worked with the substance that was later found on his body, this fact does not enable him to have a "Chezkas Tavul," because the substance was found on his body, the same body that immersed in the Mikvah. Since the substance was found on his body, it cannot be dissociated from the person himself and dealt with separately (as the knife can be dealt with independent of the Shechitah), and it must be part of the deliberation concerning the status of the person's Tevilah. Since the person did not have a "Chezkas Tavul" at the time the Safek arose, his Tevilah is deemed invalid. (This approach needs further elucidation.)

(b) TOSFOS (DH Sakin) suggests a novel approach. Perhaps the Gemara means that even if the knife had a nick at the time of the Shechitah, this does not necessarily invalidate the Shechitah. Even if the knife had a nick at the time of the Shechitah, perhaps the Shechitah was done with the part of the knife that was smooth. Since this additional doubt exists (and there is a Sfek Sfeika), the Halachah is more lenient in the case of Shechitah than in the case of Tevilah, where an intervening substance -- that was on his body during the Tevilah -- always invalidates the Tevilah.

QUESTION: The Beraisa states that if the Shochet cuts the Veshet (esophagus) of a bird and then notices that the Gargeres (trachea) is out of place, the validity of the Shechitah depends on when the Gargeres moved out of its place. If it moved before the Shechitah, then the Shechitah is invalid and the bird may not be eaten. If it moved after the Shechitah, then the Shechitah is valid and the bird may be eaten. If there is a doubt about when the Gargeres moved out of its place, then the bird may not be eaten.

RABEINU YONAH rules, based on the Gemara here, that when there is a doubt about whether the wing or leg of a bird was broken before the Shechitah (rendering it a Tereifah) or after the Shechitah, we must assume that it was broken before the Shechitah and the bird may not be eaten. (See Shulchan Aruch YD 53.)

However, Rabeinu Yonah rules differently in a similar case. In a case in which cheese was made from milk that came from an animal that was later discovered to be a Tereifah, Rabeinu Yonah rules leniently and assumes that the animal became a Tereifah immediately before the Shechitah, and the cheese is permitted. We assume that it became a Tereifah at the latest possible moment, and, until that moment, it was a Kosher animal. (See Shulchan Aruch YD 81:2.)

Why do we not use the same principle to resolve the doubt in the first case? We should assume that the bird became a Tereifah at the latest possible moment (that is, after the Shechitah), and the bird may be eaten. Why do we assume that it became a Tereifah before the Shechitah, rendering the bird unfit to eat?

ANSWER: The SHEV SHEMAITSA (5:9) explains the reasoning of Rabeinu Yonah as follows. When there is a doubt about whether the meat of an animal is prohibited because it might have been a Tereifah, we apply the principle of "Machzikin me'Isur l'Isur": when an animal was once prohibited for any reason, and there is possibility that it is still prohibited due to a different reason, the rules of Chazakah apply. The animal remains Asur until there is proof that it is Mutar. Since the animal had a Chezkas Isur when it was alive (because of "Ever Min ha'Chai" or because of "Eino Zavu'ach" -- see Insights to Chulin 9:3), when there is a doubt about whether the animal is now permitted, it retains its Chezkas Isur even though it might be Asur now because of a different reason, because of the Isur of Tereifah.

In contrast, when there is a doubt about whether the milk of an animal is permitted, we rule leniently because the milk never had a Chezkas Isur. Consequently, it had no Isur from which to be "Machzikin me'Isur l'Isur." Instead, we apply the principle of Rov that states that most animals are not Tereifos, which creates a Chezkas Heter. If the animal is found now to be a Tereifah, then it must have become a Tereifah at the latest possible moment. (See also KEREISI U'PLEISI YD 50, SHA'AREI YOSHER 3:17, Insights to Kesuvos 9:1:3.) (Z. Wainstein)

QUESTION: The Gemara (10a) originally suggests that Rav Chisda's reason for validating the Shechitah when a nick is found in the knife is the rule of "Ein Safek Motzi mi'Yedei Vadai" -- a doubt does not override a certainty. When the Shochet began the Shechitah, the knife certainly was valid, since he examined it before the Shechitah and found it to be unblemished. The doubt is whether the knife became blemished during the Shechitah or after the Shechitah. That doubt does not override the certainty that the knife was valid when the Shechitah began.

The Gemara here (10b), however, relates that Rav Chisda permitted the animals in a case in which a nick was found in a knife after thirteen animals had been slaughtered with the knife. How does the rule of "Ein Safek Motzi mi'Yedei Vadai" apply here to permit all of the animals? Why do we assume that the knife became blemished definitely after the last animal was slaughtered?

(a) RASHI (DH Michdei) explains that at this point, the Gemara assumes that Rav Chisda's reason for permitting the Shechitah is not really because of the rule of "Ein Safek Motzi mi'Yedei Vadai." Even without that logic, he permits the Shechitah because of the logic of "Sakin Isra'i, Behemah Lo Isra'i" -- the doubt involves the status of the knife and not the status of the animal (see above, Insights to 10:2). (The Gemara later retracts this assumption, as Rashi mentions later in DH Lo k'Rav Chisda.)

(b) TOSFOS (10a, DH Sakin) suggests (in one answer) that the knife definitely must have been nicked after the last Shechitah, because every Shochet is very careful not to let his knife hit the Mifrekes (the animal's neck bone, or vertebra) when he still has more animals to slaughter with this knife.

QUESTION: The Gemara concludes that when the Shochet finds a nick in his knife after slaughtering an animal, the Shechitah is valid when the Shochet cut bones with the knife after the Shechitah, because we assume that the bones caused the nick. When the Shochet did not cut any bones with the knife after the Shechitah, the Shechitah is invalid, because we assume that the knife was blemished at the time of the Shechitah. Even if the knife hit a vertebra in the neck ("Mifrekes") at the end of the act of Shechitah after it had already cut the two Simanim, we still assume that the knife was blemished at the time of the Shechitah and it was not the vertebra that blemished the knife.

Why do we not assume that a vertebra dented the knife, just as we assume that the bones cut after Shechitah dented the knife?

ANSWER: The RASHBA explains that the vertebra cannot dent a knife. The vertebra is too soft to cause a nick in the knife. Moreover, the vertebra is cut with a sawing motion and not with a cutting motion (with which the Shechitah is performed).

However, when the Shochet examined his knife, slaughtered an animal, hit a vertebra at the end of the Shechitah, slaughtered other animals, and then lost the knife before checking it for dents, we suspect that perhaps the vertebra did dent the knife and the Shechitah of the second and subsequent animals is invalid (SHULCHAN ARUCH YD 18:1, 12).

OPINIONS: The Gemara says that the Shochet is not required to give his knife to a Chacham to examine every time he performs Shechitah, because we trust the Shochet to examine the knife. Even though he is a single witness testifying to the validity of the knife, he is trusted because of the principle of "Ed Echad Ne'eman b'Isurin" -- a single witness is believed with regard to matters of prohibitions.

What is the source for the principle of "Ed Echad Ne'eman b'Isurin"?

(a) RASHI in Yevamos (88a, DH v'Amar) writes that the source for this principle is the fact that the Torah permits a person to eat at his friend's home, and it permits a man to eat in his own home (without witnessing the preparation of the food). The RITVA in Gitin (2b) quotes a Yerushalmi as Rashi's source. Where, though, does the Torah permit a person to eat food prepared by another person? Rashi here (DH Ed Echad) answers this question when he writes that the Torah permits the Kohanim to eat the meat of a Korban, even though the Torah also explicitly permits any person to perform the Shechitah of a Korban, without requiring two witnesses. The Torah clearly permits a person to eat food prepared by someone else based on his own testimony.

(b) TOSFOS in Gitin (2b, DH Ed Echad) questions Rashi's opinion and asserts that the law with regard to Shechitah does not teach that an Ed Echad is believed in other cases of Isur. Shechitah differs because it is "b'Yado," it is within the person's ability to make an animal permissible by slaughtering it properly. A person is believed to say that something is Asur or Mutar when it is in his ability, "b'Yado," to make it Asur or Mutar himself.

According to Tosfos, the source for the principle of "Ed Echad Ne'eman b'Isurin" is the law that a woman who is a Nidah is trusted to count her days of Taharah and Tum'ah by herself, as the Torah says, "v'Safrah" (Vayikra 15:28).

The BEIS HA'LEVI explains Rashi's opinion. Rashi maintains that "b'Yado" is not a reason to believe the Ed Echad in the case of Shechitah, because once the Shechitah has been performed, it is no longer within the person's ability to slaughter it again. (Z. Wainstein)

QUESTION: Rebbi Shmuel bar Nachmeni in the name of Rebbi Yonasan says that the source for relying on a Chazakah is the Torah's law that a Kohen is to examine a house that has Tzara'as, exit the house, and close the door, giving the house the status of a house with Tzara'as, a "Bayis ha'Menuga." It is clear from that law that we rely on a Chazakah, the status quo, because if we do not rely on a Chazakah, then we should suspect that before the Kohen closes the door to the house, the Tzara'as diminishes in size, becoming less than the minimum size required to make a house a Bayis ha'Menuga. It must be that we rely on the Chazakah of the house as the Kohen saw it before he exited the house.

Rav Acha bar Yakov rejects this proof. Perhaps the Kohen left the house while walking backwards, and he was able to see the Tzara'as until he actually closed the door.

The Gemara cites support for Rebbi Yonasan from a Beraisa. The verse states, "v'Yatza ha'Kohen Min ha'Bayis" -- "and the Kohen will exit the house" (Vayikra 14:38). One might have thought that the Kohen may leave the house, return to his own home, and then return later to close the door. Therefore, the verse continues, "El Pesach ha'Bayis" -- "to the entrance of the house." The Kohen must go directly to the doorway to close the door. The Beraisa later says that even if he did go to his own home first, the house nevertheless is considered a Bayis ha'Menuga, because the verse says, "v'Hisgir Es ha'Bayis" -- "and he will close the house," teaching that it attains the status of a Bayis ha'Menuga whenever the door is closed, whether the Kohen followed the proper procedure or not.

The Gemara's proof against Rav Acha bar Yakov is that the house becomes a Bayis ha'Menuga even when the Kohen went home first, returned, and then closed the door. How do we know that the Tzara'as in the house still has the minimum size? The Kohen certainly cannot see the Tzara'as from his own house! It must be that we rely on the Chazakah and assume that it still has the required size.

How does this logic disprove Rav Acha bar Yakov? Perhaps the Beraisa means that when the Kohen went home, he returned to the house and re-examined the Tzara'as and found that it still had the required size!

(a) TOSFOS and the ROSH in Nedarim (56b) explain that the Beraisa is discussing a case in which the Kohen does not actually return to the afflicted house, but rather he closes the door of the afflicted house -- while he is in his own home -- by way of a long rope that is attached to the door of the afflicted house. Alternatively, he sends an emissary to close the door. (The RAN in Nedarim mentions only the case of the rope, while the MEFARESH there (DH Yachol) mentions only the case of the emissary.)

(b) RASHI here seems to contradict himself in his explanation of the case. Originally, Rashi (DH Yachol) writes that the Beraisa is discussing a case in which the Kohen goes home, and then he returns to close the door of the afflicted house. Later, though, Rashi (DH Halach) writes that the Kohen closes the house by way of a long rope which is attached to the Bayis ha'Menuga.

The SHITAH MEKUBETZES explains that the last case, in which the Kohen closes the door by way of a rope, is the Gemara's question on Rav Acha bar Yakov. In this case, the Kohen must rely on a Chazakah that there still is a minimum size of Tzara'as in the house, since he cannot see the Tzara'as from his own house.

Why does Rashi explain the case in two different ways?

1. The MAHARSHAL (cited in the margin of the Gemara) writes that the correct text of Rashi should have both explanations in the same passage of Rashi (in DH Yachol). Preceding the second explanation, the text of Rashi should read, "Iy Nami," introducing an alternative explanation.

The Maharshal apparently understands that in the case in which the Kohen actual returns to the afflicted house to close the door, the Kohen does not take a second look at the Tzara'as in the house (unlike the opinion of the Shitah Mekubetzes), because if he did look at the Tzara'as again, then the Gemara has no proof against Rav Acha bar Yakov.

2. The MAHARAM and MAHARSHA assert that the text of Rashi does not need to be corrected. The first case of the Beraisa is intended to teach only that the Kohen is forbidden to go anywhere before he closes the Bayis ha'Menuga. By stating the first case, Rashi teaches that this is forbidden even if the Kohen comes back and closes the door in the normal manner. The second part of the Beraisa is intended to teach that the house is still considered a Bayis ha'Menuga even though the Kohen did not follow the proper Halachic procedure. Rashi here writes the case of the rope in order to teach that even if the Kohen closes the door in an unusual way, and he is not even standing near the door, the house is still considered "closed."

The Maharam continues and explains that Rashi maintains that both cases are intrinsic parts of the Beraisa. As mentioned above, it is apparent that the Beraisa is stressing that the Kohen is not supposed to leave, even temporarily, before he closes up the house. This is the source for Rashi's first explanation of the case, that the Kohen left only temporarily and then returned. The second case is equally necessary, since without that case there seems to be no question on Rav Acha bar Yakov, as mentioned above in the name of the Shitah Mekubetzes. (Y. MONTROSE)