A. [8a] Said R. Zira, said Samuel, “If he heated a knife and slaughtered with it, his act of slaughtering is valid because the sharp edge cuts through before the heat burns [the animal].” But lo there are the sides [of the slit in the throat that will be singed by the heat and that should render the act invalid.] [Not so because we have the principle that] the site of the slaughtering widens [as he cuts and the heat will not touch the sides of the throat].
B. They posed the question: if one heated up a spit and hit someone with it, is the wound to be judged as a boil or as a burning? What is the difference? [The difference is in a case as follows:] As it was taught [in the Mishnah] on Tannaite authority, A boil and a burning are declared unclean in the first week and on account of two tokens. With white hair and spreading [M. Neg. 3:4 A]. And why did [Scripture] distinguish one from another? To tell you that they cannot be combined with one another [T. Neg. 3:13 B-C][to comprise the minimum necessary to render one unclean. So the determination of whether it is a boil or a burning matters then with regard to whether it will combine with another sign].
C. And it was taught in the Mishnah on Tannaite authority, What is a boil [and what is a burning]? One was hurt (1) by a stick or (2) by a stone or (3) by olive-peat or (4) by [hot-springs of] Tiberias water — (5) whatever does not derive from fire [including even molten lead mined from its source] — lo, this is a boil. And what is a burning? One was burned by a [glowing] coal or by an ember, [boiling lime, boiling gypsum] — by anything that [is heated] by fire, [including even water heated by fire] — lo, this is a burning [M. Neg. 9:1]. And it was taught on Tannaite authority, A boil and a burning, if the boil comes before the burning, the burning nullifies the boil. And if the burning comes before the boil, the boil nullifies the burning [T. Neg 3:13 E-F]. And here what are the circumstances? As follows: he had a [wound the size of] half-a-bean to begin with. And they heated a spit and hit him with it. And a [second wound] the size of half-a-bean emerged. What is the law? Do we say that the blow comes first and the burning comes and nullifies the blow? Then the result is a case of a boil and burning which do not combine [to form the minimum size]? Or do we say that the burning comes first and the blow comes and nullifies the burning? Then the result is a case of a boil and another boil and they can combine [to form the necessary minimum]?
D. Come and take note [what was cited at A]: Said R. Zira, said Samuel, “If he heated a knife and slaughtered with it, his act of slaughtering is valid because the sharp edge cuts through before the heat burns [the animal].” So we see that the blow comes before [the burning]. Not so. [A blow caused by] a sharp blade is an exception.
E. Come and take note: If one heated up a spit and hit someone with it, the wound is judged as a burning by fire. So we see that the blow comes before [the burning]. There too [it is an exceptional case wherein] he poked him with the sharp point [so no generalization can be made from this instance].
A. Said R. Nahman, said Rabbah bar Abbuha, “The knife of a idolater — it is permitted to slaughter with it but it is forbidden to cut meat with it.” It is permitted to slaughter with it because [technically speaking] he diminishes [the value of the animal through its slaughter. It can no longer be used for breeding or work]. It is forbidden to cut meat with it because [thereby] he enhances [the value of the animal by preparing it for consumption and this is deemed to be a forbidden benefit derived from a utensil belonging to idolatry].
B. Said Raba, “There are instances [to the contrary] when one is forbidden to slaughter [with an idolater's knife because it is deemed to be a benefit]: if the animal is in danger of dying. And there are instances when it is permitted to cut meat [with an idolater's knife because it is deemed to diminish the value]: if he cuts up prime slices of meat.”
C. But should it not be the case that [cutting meat with an idolater's knife] is forbidden on account of the [forbidden] fat [stuck to it that then renders the meat unfit]? [8b] [We could say we are dealing with] a new one [i.e., a knife with no fat on it].
D. [However we could object to this line of reasoning.] A new one, according to both R. Ishmael and R. Aqiba, has the status of a utensil used to serve idolatry. And [we have a principle that] a utensil used to serve idolatry is not forbidden until it is put into service. [Hence there is no reason to deem a new knife to be forbidden whether he cuts prime cuts with it or ordinary cuts of meat.]
E. Another possibility: he already cut with it wood for idolatry. Or another possibility: we are talking about an old knife that had been heated in a fire [leaving no trace of fat on it].
A. It was stated: One who slaughters with a knife belonging to idolaters — Rab said, “He must cut a strip [of meat from the throat where it touched the knife].” Rabbah bar bar Hannah said, “He must wash [the throat where the knife touched it].”
B. Let us say that the dispute is over the following [principle of the law]. One considers that the site of slaughtering [at the throat] is cold and the other considers that the site of slaughtering is boiling hot [because of the body heat of the animal's blood. In the latter case the meat will readily absorb from the forbidden fats on the knife.]
C. No. Both authorities agree that the site of slaughtering is boiling hot [because of the body heat of the animal's blood]. So according to the one who holds the view that he must cut away a strip, that makes perfect sense. But according to the one who holds the point of view that he must wash it, [the explanation must be that he maintains that] because the organs are actively spurting out blood, the flesh cannot absorb [forbidden fat].
D. Alternatively both may hold the view that the site of slaughtering is cold. The one who holds the view that he must wash it, that makes perfect sense. But according to the one who holds the point of view that he must cut away a strip, [the explanation must be that he maintains that] because of the pressure on the knife, [the flesh] will absorb [forbidden fat].
A. [Concerning the status of] a knife used to slaughter an animal found to be a terefah — there was a dispute about this between R. Aha and Rabina. One says he must wash it in hot water. And the other says he may wash it even in cold water. And the law is: even in cold water.
B. And if they have a cloth rag handy to wipe [the knife], he needs to do nothing more.
C. But according to the view that he must wash it in hot water, what is the basis for this opinion? Because it had absorbed forbidden substance [from the terefah]. [The objection is raised: according to this reasoning any knife used in the slaughter] of a permitted animal also absorbs [forbidden substance from the] limb of a living animal [i.e., before the completion of the act of slaughter it absorbs from the living animal which is forbidden]. [Not so.] When does [the knife] absorb? When it is hot. When is it hot? When it finishes slaughtering. And at that time the animal is permitted.
A. Said R. Judah, said Rab, “The butcher [who slaughters] must have three knives: one for slaughtering, one for cutting meat, and one for cutting forbidden fats.” And why not designate one [knife for two tasks]? And he could cut the meat with it and afterward cut the fats with it. [No. We fear] lest he first cut the fats with it and afterward the meat with it. Here too [if he has two knives] he may mix them up! [No.] Since he has two he will be able to distinguish between them.
B. And said R. Judah, said Rab, “The butcher must have two vessels with water. In one he washes the meat and in the other he washes the fats.” And why not designate one [vessel for two tasks]? And he could wash the meat in it and then wash the fats in it? [No. We fear] lest he first wash the fats in it and afterward wash the meat in it. Here too [if he has two vessels] he may mix them up! [No.] Since he has two he will be able to distinguish between them.
C. Said Amemar in the name of R. Pappa, “One should not stack the loins [kidneys] on top of [other] meat because the fat [from the loins] will drip and the meat will absorb it.” If so when they [the loins] lie naturally we also [ought to fear] that the fat will drip and the meat will absorb it. [No.] The membrane [around the fat] separates it from [the meat] underneath it. If so, [9a] when [the loins] are on top [of other meat] there is also a membrane [to separate the fats from the meat]. [We cannot say this.] Since the butcher handles it [the membrane] disintegrates.