The Gemara challenges: According to this logic, one can also derive the halakha that the forbidden fat of the carcass of a non-kosher animal is impure from the verse: ''And the fat of a carcass, and the fat of a tereifa, may be used for any other service'' (Leviticus 7:24), which teaches that such forbidden fat is ritually pure.

The continuation of the verse: ''But you shall in no way eat of it,'' indicates that the verse renders pure only fat that is forbidden specifically due to the prohibition: You shall not eat the forbidden fat of a carcass, i.e., the forbidden fat of kosher animals. This serves to exclude this forbidden fat of a non-kosher animal, which is not forbidden due to the prohibition: You shall not eat the forbidden fat of a carcass, but rather due to the prohibition against eating a non-kosher animal. Since the verse that states that fats are ritually pure is referring only to kosher animals, the forbidden fat of a carcass of a non-kosher animal must be impure. Rav Sheizevi’s derivation of this halakha from the word tereifa is therefore superfluous.

Rather, this word ''tereifa'' is necessary to include the forbidden fat of a carcass of a kosher undomesticated animal, to teach that it is ritually pure; as it might enter your mind to say that only the forbidden fat of carcasses of those animals whose fat is forbidden and whose meat is permitted if slaughtered, i.e., kosher domesticated animals, is ritually pure, and this serves to exclude this forbidden fat of carcasses of those animals whose fat and meat are both permitted if slaughtered, i.e., kosher undomesticated animals, whose fat is impure. To counter this possibility, the word ''tereifa'' teaches us that the fat of a carcass of any animal that can become a tereifa is ritually pure, including the fat of kosher undomesticated animals.

He said to him: If it is derived from the verse that the forbidden fat of a carcass of a kosher undomesticated animal is pure, what is different about a non-kosher animal that would cause its forbidden fat to be impure? If the difference is that its fat is not distinct from its meat, as both are forbidden for consumption, the fat of a kosher undomesticated animal is also not distinct from its meat, as both are permitted. And furthermore, isn’t it written later in the verse: ''But you shall in no way eat of it'' (Leviticus 7:24)? This phrase is interpreted (70b) as excluding the fat of undomesticated animals, teaching that it is impure.

Rather, Abaye said: The word ''tereifa'' in this verse was necessary for its own sake, to teach that the forbidden fat of a carcass of a tereifa of a kosher domesticated animal is pure. The inclusion of the word teaches that you should not say that since a non-kosher animal is forbidden while still alive, and a tereifa is forbidden while still alive, therefore just as the forbidden fat of a non-kosher animal is impure, so too the forbidden fat of a tereifa is impure. The word ''tereifa'' therefore teaches that it is pure.

The Gemara asks: But if so, i.e., if one could have learned the halakha of the forbidden fat of a tereifa from the halakha of the forbidden fat of a non-kosher animal, then this word ''tereifa'' in the verse concerning the impurity of a kosher bird carcass (Leviticus 17:15) is also necessary for its own sake, to teach that the carcass of a kosher bird that is a tereifa is impure. It is necessary for this to be written with regard to the carcass of a kosher bird so that you should not say as follows: Since a non-kosher bird is forbidden for consumption, and a tereifa is forbidden for consumption, therefore just as a non-kosher bird does not impart impurity, so too a tereifa does not impart impurity. According the Rabbi Yehuda, the word is necessary to include the slaughtered kosher bird that is a tereifa, not a carcass.

And furthermore, is it possible to derive the halakha concerning a tereifa from that concerning a non-kosher animal, as suggested? The two cases are incomparable, as a non-kosher animal never had a kosher period before being forbidden, whereas a tereifa had a kosher period before becoming a tereifa. And if you would say: What can be said with regard to an animal that is a tereifa from the womb, which never had a kosher period? In any event, there are kosher animals among its species, i.e., the tereifa is a member of a kosher species, which cannot be said of a non-kosher animal.

Rather, Rava said: The word tereifa in the verse concerning forbidden fat (Leviticus 7:24) teaches a different halakha. By stating: ''But you shall in no way eat of it,'' referring to the forbidden fat of a carcass, the Torah states: Let the prohibition of eating a carcass come and take effect where the prohibition of eating forbidden fat already exists. One who eats the forbidden fat of a carcass is liable both for eating forbidden fat and for eating from a carcass. Likewise, the word ''tereifa'' in the verse teaches: Let the prohibition of eating a tereifa come and take effect where the prohibition of eating forbidden fat already exists, so that one who eats the forbidden fat of a tereifa is liable for transgressing two prohibitions.

And both the word ''carcass'' and the word ''tereifa'' are necessary, even though they teach similar halakhot. As, had the verse taught us about additional liability only with regard to the forbidden fat of a carcass, one might have thought that it applies to only a carcass, as it imparts ritual impurity, but with regard to a tereifa, which does not, one might say that the additional liability does not apply. And had the verse taught us this halakha only with regard to a tereifa, one might have thought that it applies only to a tereifa, as its prohibition takes effect while it is still alive, but with regard to a carcass, which becomes forbidden only when it dies, one might say that it does not apply. Both words are therefore necessary.

§ The Gemara has established that according to Rabbi Yehuda, the word ''tereifa'' in the verse concerning the impurity of a kosher bird carcass (Leviticus 17:15) teaches that a slaughtered bird that is a tereifa imparts ritual impurity. The Gemara asks: And what does Rabbi Meir, who holds that a slaughtered bird that is a tereifa does not impart ritual impurity, do with this word ''tereifa''? The Gemara answers: It is necessary to exclude the slaughter of non-sacred birds that occurs inside the Temple courtyard, teaching that it does not cause them to impart ritual impurity as would a carcass, even though they are forbidden for consumption.

And how does Rabbi Yehuda derive this halakha? The Gemara answers: Another instance of the word tereifa is written concerning the ritual impurity of birds: ''A carcass, or a tereifa, he shall not eat to become impure with it'' (Leviticus 22:8). Rabbi Yehuda derives the halakha from this verse.

And how does Rabbi Meir interpret the appearance of the word tereifa in both verses? The Gemara answers: One is necessary to ex-clude the slaughter that occurs inside the Temple courtyard as mentioned above, and one is necessary to exclude a non-kosher bird, to teach that the carcass of a non-kosher bird does not impart ritual impurity.

And how does Rabbi Yehuda derive that the carcass of a non-kosher bird does not impart ritual impurity? The Gemara answers: He derives it from the word ''carcass'' in the verse: ''A carcass, or a tereifa, he shall not eat to become impure with it'' (Leviticus 22:8), which indicates that only carcasses of birds that are forbidden for consumption due to their status as a carcass are impure. Non-kosher birds are forbidden due to their non-kosher status, not due to their status as a carcass.

The Gemara asks: And what does Rabbi Meir do with this word ''carcass''? The Gemara answers: Since the verse mentions eating, Rabbi Meir holds that the word ''carcass'' is written to teach that the minimum measure of consumption of the meat of a bird carcass that renders one impure is an olive-bulk, which is the standard legal measure of consumption for Torah laws in general.

The Gemara challenges: But let him derive this measure from the first verse: ''And every soul that eats a carcass…shall be impure'' (Leviticus 17:15), from the fact that the Merciful One expresses this halakha using the language of consumption.

The Gemara responds: Both verses are necessary, one to indicate that the measure of consumption that renders one impure is an olive-bulk, and one to indicate that the maximum measure of time for consumption of the olive-bulk is the time it takes to eat a half-loaf of bread. One who takes longer than this standard measure of time will not contract impurity.

It is necessary for the Torah to indicate this latter halakha as well, as otherwise it might enter your mind to say: Since the impurity of carcasses of birds is a novelty, as one contracts it by eating rather than by touching or carrying, perhaps its halakhot are unusually stringent and even one who eats an olive-bulk in more than the time it takes to eat a half-loaf of bread should also contract impurity. Therefore, the verse teaches us otherwise.

§ The Gemara cites a baraita concerning the impurity of the forbidden fat of a carcass. The Sages taught: When the verse: ''And the fat of a carcass, and the fat of a tereifa, may be used for any other service'' (Leviticus 7:24) teaches that such fat is pure, the verse speaks of the forbidden fat of a kosher animal.

The baraita challenges: Do you say that the verse speaks of the forbidden fat of a kosher animal, or perhaps does it only speak of the forbidden fat of a non-kosher animal?

You may say in response: The Torah renders a slaughtered animal pure of the impurity of a carcass due to the fact that it was ritually slaughtered. And likewise the Torah renders the forbidden fat of a carcass pure, due to the fact that it is forbidden fat. Therefore, the two cases are comparable: Just as when the Torah renders a slaughtered animal pure due to the fact that it was slaughtered, it is referring only to a kosher animal and not to a non-kosher animal, which is impure even when ritually slaughtered, so too, when the Torah renders forbidden fat pure due to the fact that it is forbidden fat, it is referring only to a kosher animal and not to a non-kosher animal.

The baraita challenges: Or perhaps go this way and maintain that since the Torah renders the carcass of a non-kosher animal ritually pure, removing it from the category of a carcass, and likewise the Torah renders the forbidden fat of a carcass pure, due to the fact that it is forbidden fat; therefore, the two cases are comparable: Just as when the Torah renders the carcass of a non-kosher animal pure, removing it from the category of a carcass, it is referring only to a non-kosher animal and not to a kosher animal, the carcass of which imparts impurity, so too, when the Torah renders forbidden fat pure due to the fact that it is forbidden fat, it is referring only to a non-kosher animal and not to a kosher animal.

You may say in response: