Midrash su Levitico 22:8

3) I would know that only their meal-offerings (are permitted to Cohanim). Whence do I derive that their melikah (bird-offerings are also permitted to be eaten by Cohanim)? R. Shimon says: (If not apprised otherwise) I would read (Vayikra 22:8): "Neveilah (carcass [including, ostensibly, a melikah offering] or treifah (an organically "torn" animal) he (a Cohein) shall not eat to defile himself therewith" (If he does eat it, he is forbidden to eat kodshim). It is, therefore, written: "for Aaron and for his sons," to permit the melikah offerings of Israelites.

5) I might think that the neveilah of a beast confers tumah upon clothing (when it is) in the esophagus; it is, therefore, written (Vayikra 22:8) "A neveilah and a treifah he shall not eat to become unclean." (The allusion is to the neveilah of an animal [i.e., a bird],) which confers tumah only by being eaten — to exclude the neveilah of a beast, which confers tumah (even) before it is eaten.

6) I might then think that the neveilah of a bird confers tumah (in the esophagus) by Scriptural edict, and that of a beast, a fortiori (viz.: If the neveilah of a bird, which does not confer tumah by touch, does so by being eaten, how much more so, the neveilah of a beast, which does confer tumah by touch!) It is, therefore, written (Vayikra 22:8) ("to become unclean through it" [the neveilah of a bird]) — Only through it is tumah conferred upon clothing by being swallowed, and not through the neveilah of a beast.

7) I might think that the carrion of a beast would confer tumah upon one's clothes (if stuffed) into his esophagus (without his having touches or carried it, it being written (Vayikra 11:40) "And he who eats it shall wash his clothes"); it is, therefore, written (Vayikra 22:8) "Carcass or treifah he shall not eat to become tamei through it" — (We are speaking of that [a bird]) which confers tumah only through eating (and not through touching or carrying), excluding a beast, which confers tumah before it is eaten (by touching or carrying). I might think that bird carcass confers tumah according to Scripture, and beast carcass, a fortiori; it is, therefore, written "through it" — Through "it" (bird carcass) confers tumah in the esophagus, and not beast carcass. If so, why is it written (in reference to beast carcass, Vayikra 11:40) "And he who eats? To assign a (minimum) amount for (tumah of) touching and carrying — Just as for "eating," an olive-size, so, for "touching," an olive-size.

9) if the kidneys were removed; if the spleen were removed; if the lower jaw were removed; if the womb were removed; if the (lungs) were shrunk by some natural shock, (such as thunder) (I might think that these are considered treifah); it is, therefore, written (Vayikra 22:8): "neveilah (carrion) or treifah (he shall not eat") — Just as neveilah is not alive, so treifah is not viable, to exclude the above, which are viable.

12) (Vayikra 22:8) ("A neveilah [the carcass of an animal that died by itself] and a treifah [a torn animal] he shall not eat to become unclean thereby; I am the L–rd.") I might think that the neveilah of an unclean beast made one's clothing unclean upon entering the esophagus; it is, therefore, written "A neveilah and a treifah he shall not eat to become unclean" — what confers tumah only by being eaten, to exclude the neveilah of a beast, which confers tumah before being eaten (by being touched or carried).

13) I might think that the neveilah of a bird confers tumah via the verse and the neveilah of a beast, a fortiori, [viz.: If the neveilah of a bird, which does not confer tumah by being touched or carried, does confer tumah in the esophagus, then the neveilah of a beast, which does confer tumah by being touched or carried, how much more so should it confer tumah in the esophagus!) It is, therefore, written "to become unclean thereby. Tumah is conferred thereby (i.e., a by a bird) in the esophagus, and not by the neveilah of a beast.

"and flesh in the field, treifah ("torn"): This tells me only of the field. Whence do I derive (that a treifah is forbidden also) in the house? From (Leviticus 22:8) "Neveilah (carrion) and treifah he shall not eat." Treifah is likened to neveilah. Just as neveilah is forbidden both in the house and in the field, so, treifah. If so, why is "field" (specifically) written here? Scripture speaks of the common instance. Similarly, (in respect to a ravished maiden) (Devarim 22:27) "For in the field he found her" — Scripture speaks of the common instance. Similarly (Ibid. 20:6) "Who is the man who has planted a vineyard?" This tells me only of a vineyard. Whence do I derive (the same for) all trees? Scripture speaks of the common instance. Here, too, "in the field treifah" — Scripture speaks of the common instance.