Midras Ulangan 14:21: Otzar Midrashim, Mekhilta DeRabbi Yishmael & Midrash Tanchuma Buber

One Torah... (Exodus 12:49). And it is written "You shall not eat any carcass; you shall give it to the stranger in your gates and he shall eat it" (Deuteronomy 14:21). You find the Holy One Blessed Be He shows affection for converts and commands about them everywhere. And here He says to give the carcass to the stranger? Rabbi Bunai said in the name of Rabbi Nehorai: In forty-eight places the Holy One Blessed Be He warned about converts, and commanded them [correspondingly] in forty-eight places about idolatry... Rabbi Antonikius said in the name of Yehuda ben Simon: The Holy One Blessed Be He said: I take vengeance upon... the idolater, and this one separated from it and came to convert. Therefore I warn about him [to Israel] corresponding to idolatry. Until now... wise Haman "The stranger" (that is Abraham, see below) (Psalms 88), and similarly "I called an eagle from the east" (Isaiah 46:11). "You shall not eat any carcass; you shall give it to the stranger in your gates and he shall eat it" - the verse does not speak about a convert who converted, but about a stranger who is outside... You find that one who is doubtful about converting... Therefore it says "to the stranger in your gates" - one who comes and goes through your gates. You find four types of converts: One corresponds to the Levite, "And you shall give to the Levite, to the stranger, to the orphan, and to the widow" (Deuteronomy 26:12). One corresponds to the poor, as it says "And you shall leave them for the poor and the stranger" (Leviticus 19:10). And one corresponds to an animal, as it says "Both your animals and the stranger in your gates" (Exodus 20:10). And one corresponds to the maidservant, as it says "so that your manservant and stranger may rest" (Exodus 23:12). Why? For these four converts convert for the sake of something different each. And therefore He compares each one to that thing he converted for the sake of. The Holy One Blessed Be He said: There is nothing beloved before Me like one who converts for the sake of My holy name. Just as among all the tribes there is nothing as beloved to Me as the tribe of Levi, so among all converts there is nothing as beloved before Me as you. Therefore He compares him to Abraham, as it says "The stranger shall be like the native" (Leviticus 24:22).

R. Nathan says: The verse "under its mother" comes to be expounded, viz.: "under its mother" — after its mother has died. You say "under its mother" — after its mother, but perhaps it is to be understood literally, (i.e., near its mother)? — You reason thus: It is written here "its mother," and elsewhere, "its mother" ([Devarim 14:21] "You shall not cook a kid in its mother's milk.") Just as there, (the meaning is "(milk) of the same kind" (as it is, i.e., both it and the milk being of the same source), so, here, "of the same kind." [This has a specific halachic implication.]

(Exodus 22:30) "And men of holiness shall you be to me": R. Yishmael says: When you are holy, you are Mine. Issi b. Yehudah says: When the Holy One Blessed be He originates a mitzvah for Israel, He adds holiness to them. Issi b. Guriah says: It is written here (Devarim 14:21) "holy" ("for a holy people are you … You shall not cook a kid in its mother's milk"), and, elsewhere (Exodus, Ibid.) "holiness." Just as here ("a kid, etc.") the prohibition is eating, so, there, ("treifah") the prohibition is eating.