מדרש אויף במדבר 18:8

(Exodus 12:1) "And the L–rd spoke to Moses and to Aaron in the land of Egypt, saying": I might think that both Aaron and Moses were being addressed; it is, therefore, written (Exodus 6:28) "And it was on the day that the L–rd spoke to Moses in the land of Egypt": Only Moses was being addressed and not Aaron. If so, why is it written "to Moses and to Aaron"? We are hereby taught that just as Moses was "included" in the words (i.e., by their being spoken to him), so, Aaron was included in the words (i.e., by his "overhearing" them). And why did He not speak (directly) to him? In deference to Moses. We find Aaron, then, to be excluded from all the (direct) addresses in the Torah except for three (Leviticus 10:8, Numbers 18:1, Numbers 18:8), where it is impossible (to understand otherwise).

(Numb. 16:7) YOU LEVITES HAVE GONE TOO FAR! See, I have told you! Were they not fools, in that when he gave them this warning, they took it upon themselves <to offer sacrifice>?²⁷The bracketed words of explanation occur in the parallel accounts of Tanh., Numb. 5:12; Numb. 18:8. They had sinned against their own lives, as stated (in Numb. 17:3 [16:38]): THE CENSERS OF THESE WHO HAVE SINNED AT THE COST OF THEIR LIVES. Now since Korah was a clever man, how did he see fit to commit this folly? It is simply that his eyes misled him. He foresaw a great lineage stemming from himself, <e.g.,> Samuel, who was the equivalent of Moses and Aaron. Moreover, the twenty-four <Levitical> courses would stem from his sons, all of whom would prophesy by the Holy Spirit, [as stated] (in I Chron. 25:5): ALL THESE WERE SONS OF HEMAN,²⁸A descendant of Korah. THE KING'S SEER IN MATTERS PERTAINING TO GOD FOR HIS GREATER GLORY. He said: Is is possible that, when this greatness is going to stem from me, I should perish? But he did not foresee correctly, since his children would repent, and those < great ones> would stem from them. Thus did he foresee.²⁹The two parallels read: “But Moses did foresee this.” He therefore acted the fool in going against that statute, when he heard from the mouth of Moses that they all would perish but one would escape. (Numb. 16:7:) THEN IT SHALL COME TO PASS THAT THE MAN WHOM THE LORD CHOOSES IS THE HOLY ONE.

(Bamidbar 18:8) "And the L-rd spoke to Aaron": I would think (the intent is) that the speaking was to Aaron; it is, therefore, written (Ibid. 17:5) "A sign for the children of Israel … as the L-rd spoke to Moses about him" (Aaron, viz., that only he and his sons are to be Cohanim), whereby we are apprised that the speaking was to Moses, to tell to Aaron. (Bamidbar, Ibid.) "And I, behold, (I have given to you") with joy, (the twenty-four priestly gifts.) These are the words of R. Yishmael — whereupon his disciples said to him: But master, it is written (Bereshit 6:17) "And I, behold, shall bring a flood of water, etc." Are we, then to assume that this was a joy to Him? He answered: When His angerers go lost from the world, it is a joy to Him. And thus is it written (Proverbs 11:10) "When the righteous prosper, the city exults, and when the wicked perish there is rejoicing." And (Psalms 3:9-10) "You have broken the teeth of the wicked. Deliverance is the L-rd's. Upon Your people are Your blessings, selah." And (Ibid. 10:16) "The L-rd is King for ever and ever. Nations have gone lost from His land." And (Ibid. 104:35) "Sinners will end from the earth, and the wicked will be no more. Bless the L-rd, O my soul, Hallelukah!" R. Nathan said to him: I will add to your words: "And I" — willingly; "behold" — with joy. And thus is it written (Shemot 4:14) "Behold, he (Aaron) is going out to meet you (Moses; and when he sees you, he will rejoice in his heart."