Rabbi Yehuda says: Its status is like any other carcass of an unslaughtered kosher bird, and its meat renders one who swallows it ritually impure.

Rabbi Meir said: My opinion can be inferred a fortiori. If an animal carcass transmits impurity to a person through touching it and through carrying it, and nevertheless the slaughter of an animal purifies it, even if it is a tereifa, from its impurity, i.e., its slaughter prevents it from assuming the impurity status of a carcass, then with regard to a bird carcass, which possesses a lesser degree of impurity, as it does not transmit impurity to a person through touching it and through carrying it, but only through swallowing it, is it not logical that its slaughter should purify it, even if it is a tereifa, from its impurity?

And once it is established that slaughter renders a bird that is a tereifa pure, it can be inferred that just as we found with regard to its slaughter that it renders a bird fit for consumption and purifies a bird, even if it is a tereifa, from its impurity, so too its pinching, which renders a bird offering fit with regard to consumption, should purify it, even if it is a tereifa, from its impurity.

Rabbi Yosei says: Although one can derive from the case of an animal that slaughter renders even a bird that is a tereifa pure, that derivation cannot be extended to pinching. The same restriction that applies to every a fortiori inference, namely, that a halakha derived by means of an a fortiori inference is no more stringent than the source from which it is derived, applies here: It is sufficient for the halakhic status of the carcass of a bird that is a tereifa to be like that of the carcass of an animal that is a tereifa; its slaughter renders it pure, but its pinching does not.

GEMARA: In the mishna, Rabbi Yosei answers Rabbi Meir by invoking the principle that a halakha derived by means of an a fortiori inference is no more stringent than the source from which it is derived. The Gemara asks: And does Rabbi Meir not require that a fortiori inferences conform to the principle that it is sufficient for the conclusion that emerges from an a fortiori inference to be like its source? But isn’t the principle: It is sufficient, etc., mandated by Torah law?

As it is taught in a baraita: How is it derived from the Torah that derivation by means of an a fortiori inference is a valid method of biblical exegesis? The Torah states with regard to Miriam, who was reprimanded by God: “And the Lord said to Moses: If her father had but spit in her face, should she not hide in shame seven days? Let her be shut up outside the camp seven days” (Numbers 12:14). If one who was reprimanded by her father would hide in shame for seven days, one could infer through an a fortiori inference that one reprimanded by the Divine Presence should be shut up outside the camp for fourteen days. Rather, one must say: It is sufficient for the conclusion that emerges from an a fortiori inference to be like its source.

Rabbi Yosei, son of Rabbi Avin, said: Rabbi Meir does require that a fortiori inferences conform to this principle. But he does not actually infer his opinion a fortiori; rather, he found a verse and interpreted it.

The Torah states, with regard to the impurity of unslaughtered animal carcasses: “This is the law of the beast, and of the fowl” (Leviticus 11:46), indicating that the two are somehow equated. But with regard to what law is a beast equal to a fowl and a fowl equal to a beast? The halakhot of ritual impurity governing animals and birds are not comparable; an animal transmits impurity by touching and by carrying, whereas a bird does not transmit impurity by touching or by carrying. Furthermore, a bird renders the garments of one who swallows it ritually impure when it is in the throat; an animal does not render the garments of one who swallows it ritually impure when it is in the throat.

Rather, this verse serves to tell you that just as with regard to an animal, that which renders it fit for consumption, i.e., slaughter, purifies it, even when it is a tereifa, from its impurity, so too with regard to a bird, that which renders it fit for consumption, i.e., both the slaughter of a non-sacred bird and pinching the nape of a bird offering, purifies a bird, even if it is a tereifa, from its impurity.

§ The Gemara asks: And what is the reasoning of Rabbi Yehuda, who holds that a bird that is a tereifa imparts impurity even when slaughtered? He too found a verse and interpreted it. The Torah states with regard to the ritual impurity of kosher bird carcasses: “And every soul that eats a carcass, or a tereifa…he shall be impure until the evening” (Leviticus 17:15). Rabbi Yehuda said: Why was the case of a tereifa stated? If the verse is referring to a live tereifa, it should not be impure, as the term “a carcass” is stated, indicating that to impart impurity the bird must be dead. If it is referring to a tereifa that is not alive, but rather has died of its wounds, it falls within the category of a carcass. Rather, the word tereifa is written to include a tereifa that one slaughtered before it had the opportunity to die by itself, to teach that it imparts ritual impurity as would a carcass.

Rav Sheizevi said to the Sage who suggested this source for Rabbi Yehuda’s opinion: If that is so, one should interpret another verse likewise, as it is written: “And the fat of a carcass, and the fat of a tereifa, may be used for any other service” (Leviticus 7:24), meaning that although the meat of a carcass imparts ritual impurity, those fats that would be forbidden even if the animal had been slaughtered do not impart impurity.

There too let us say, interpreting the verse according to Rabbi Yehuda’s logic: Why is the case of a tereifa stated? If it is referring to a live tereifa, the case is superfluous, as “a carcass” is stated. Since the forbidden fat of a carcass is pure, obviously that of a live animal is pure. If it is referring to a tereifa that is not alive, but has rather died of its wounds, it is included within the category of “a carcass,” and likewise it need not be mentioned. Rather, the word “tereifa” is written to include a tereifa that one slaughtered, to teach that its forbidden fat is pure. By inference, one should then conclude that its meat does impart impurity.

But doesn’t Rav Yehuda say that Rav says, and some say it was taught in a baraita: The verse concerning the impurity of carcasses states: “And if some animal, of which you may eat, dies, one who touches its carcass shall be impure” (Leviticus 11:39)? The word “some” teaches that some animals impart impurity and some animals do not impart impurity. And what is it that does not impart impurity? That is a tereifa that one slaughtered. And if even its meat does not impart impurity, the word tereifa is not needed to teach that its forbidden fat is pure.

Rather, the word tereifa in the verse concerning forbidden fat (Leviticus 7:24) is necessary to exclude non-kosher animals from the halakha in the verse and to teach that their forbidden fat is impure. The word indicates that only the forbidden fat of those carcasses to whose species the halakha of tereifa applies, i.e., those of kosher animals, impart impurity. Forbidden fat of a carcass of a non-kosher animal is excluded, as the halakha of tereifa does not apply to its species. The status of tereifa is immaterial for a non-kosher animal as its consumption is prohibited in any event.

Here too, the word tereifa in the verse concerning the impurity of kosher bird carcasses (Leviticus 17:15) should be interpreted as excluding a carcass of a non-kosher bird from ritual impurity, as the halakha of tereifa does not apply to its species. Therefore, this verse cannot serve as a source for Rabbi Yehuda’s opinion with regard to the impurity of a slaughtered bird that is a tereifa.

The Gemara responds: According to Rabbi Yehuda, the halakha that carcass of a non-kosher bird does not impart impurity is derived from the phrase “a carcass” as it appears elsewhere.

As it is taught in a baraita that Rabbi Yehuda says: One might have thought that the carcass of a non-kosher bird renders the garments of one who swallows it ritually impure when it is in the throat. But the verse states, concerning the impurity of carcasses of birds: “A carcass, or a tereifa, he shall not eat” (Leviticus 22:8). This type of impurity applies only to those birds that are forbidden specifically due to the prohibition: You shall not eat of a carcass, i.e., kosher birds that died without ritual slaughter. This carcass of a non-kosher animal is excluded, and is not impure, as it is forbidden not due to the prohibition: You shall not eat of a carcass, but rather due to the prohibition: You shall not eat a non-kosher bird, to render yourself impure with it. Consequently, the word tereifa in the aforementioned verse (Leviticus 17:15) teaches that a slaughtered tereifa imparts ritual impurity, as originally posited.