Midrash for Numbers 8:17

(Exod. 25:2): SPEAK UNTO THE CHILDREN OF ISRAEL, <AND LET THEM TAKE FOR ME A PRIESTLY SHARE>. It is not written here: "And let them take a priestly share," but AND LET THEM TAKE FOR ME (li) A PRIESTLY SHARE. Anything about which li ("to me" or "for me") is used, <belongs to the Holy One> in this world and in the world to come.¹³Lev. R. 2:2; Sifre to Numb. 11:16 (92); cf. Numb. R. 15:17; cf. below, Tanh. (Buber), Exod. 8:9. (Lev. 25:23:) BUT THE LAND MAY NOT BE SOLD PERMANENTLY, FOR [THE LAND] BELONGS TO ME (li), in this world and in the world to come. [(Numb. 8:17:) FOR EVERY FIRST-BORN AMONG THE CHILDREN OF ISRAEL BELONGS TO ME (li), in this world and in the world to come. (Numb. 8:14:) AND THE LEVITES SHALL BELONG TO ME (li), in this world and in the world to come.] So also the priestly share <belongs to the Holy One> in this world and in the world to come.

"And take the Leviim for me" (Numbers 3:41), that they will be taken for My Name. "I am the Eternal" (ibid.), I am trusted to pay a good reward that they are taken for my name. "In place of every firstborn among the Children of Israel" (ibid.), since the firstborns are Mine, as it says (Numbers 8:17) "For Mine is every firstborn [...] on the day that I smote every firstborn in the land of Egypt... [I consecrated them to Myself]", the Holy Blessed One says, for the sake of their obligation of Israel I changed the order of the world. With which side did I write in the Torah that a donkey may be redeemed with a lamb, as it says (Exodus 13:13) "The firstborn [lit. "opening"] of every donkey you shall redeem with a sheep"? I didn't do this; rather, I redeemed a sheep with a donkey. The Egyptians are called a donkey, as it says (Ezekiel 20:2) "That the flesh of donkeys is their flesh" and Israel is called a sheep, as it says (Jeremiah 50:17) "Israel is a scattered sheep". And I murdered their firstborn, and I sanctified the firstborn of Israel, as it says "For Mine is every firstborn among the children of Israel ... on the day that I struck all the firstborn ... [of Egypt]" (Numbers 3:41). And the animals of the Leviim in place of all the firstborns amongst the animals of the Children of Israel, that they you brought out to kill the place the firstborn of the animals of Egypt, and saved the animals of Israel, and therefore sanctified to His Name the firstborn of the animals of Israel, and since he says "For Mine is every firstborn among the children of Israel ... on the day that I struck all the firstborn ... [of Egypt]" (Numbers 3:41).

5. R. Shimon Ben Yochai taught: Moses could not have known the exact moment, nor the approximate minute, nor the general time at night. This is why he said “About midnight.” (Ex 11:4) However, the Kadosh Baruch Hu knew the exact moment, and the approximate minute, and the general time at night. That is why God entered [without being early or late] by a hair's breadth. So who was it that divided [the hours of the night]? R. Benjamin bar Jafet in the name of R. Yohanan, the night divided itself. Our Rabbis say that the Creator divided it. Here it says, “And it came to pass at midnight” (Ex 12:29) and elsewhere it says, “And he divided the night against them.” (Gen 14:15) Rabbi Tanchuma said: Your father set out with Me at midnight, and I will set out with his children and midnight. The Rabbis said: the Kadosh Baruch Hu said, “your father set out with Me from last night until midnight, and I will set out with his children from midnight until the morning.” R. Yonatan said: The angel guarding over Egypt cannot fall except during the day. What is the reasoning? [From the verse] At Tehaphnehes also the day shall withdraw itself, when I shall break there the yokes of Egypt, and the pride of her power shall cease in her; [as for her, a cloud shall cover her, and her daughters shall go into captivity.](Ez 30:18) [Elsewhere it also] says, In that day there shall be five cities in the land of Egypt that speak the language [of Canaan, and swear to the LORD of hosts; one shall be called the city of destruction. ] (Is 19:18) Which five cities are these? R. Hilkiah said in the name of R. Simon: Noa, Noph, Tehaphnehes, the City of Destruction, and the City of the Sun; Noa is Alexandria, Noph is Memphis, Tehaphnehes is Hophnias, the City of Destruction is Sharakani, and the City of the Sun is Heliopolis. R. Yohanan ben Zakkai said: We have found both night and day referred to as “day,” as it is written: And there was evening and there was morning, one day. (Gen 1:5) R. Joshua bar R. Nechamah understood [the same claim] from this: Even the darkness is not too dark for Thee, but the night shineth as the day; the darkness is even as the light.(Ps 139:12) Darkness is [the same as] lightness to Me, and [only] human beings consider it night. This is what is meant [by saying] it was on the day that the firstborn of Egypt died [although it was midnight]. This is how [it happened]: They were afflicted with the deadly curse in evening time, then their bodies shook all night, and then they died in the day time. What is the reasoning? [Because] It is not written “All of us have all died,” but rather “All of us are dying ” (Ex 12:33) Then they went and died . As it is written: On the day that I struck down all the first-born [of the Land of Egypt] (Num 3:13), and further on it says, on the day that I sanctified all the firstborn to Me (paraphrase of Num 8:17 ). On this basis one may conclude that it was on the very same day that the firstborn of Egypt died, which [God said], “on this day I have sanctified to me the firstborn [of the Israelites].”