Midrasz do Kapłańska 8:3

4) (Vayikra 8:3): ("And assemble all of the congregation at the door of the tent of meeting": Do it in the presence of the entire congregation so that they accord honor to the priesthood. (Vayikra 8:4): "And Moses did as the L–rd commanded him.": Just as Moses had set forth the (sacrificial) service of the sanctuary, he set forth the service of the Cohanim and the Levites, the vestments of each (Cohein) according to his (sacrificial) function.

(Numb. 20:7-8:) “Then the Lord spoke unto Moses saying, ‘Take the rod... and you shall provide the congregation and their cattle with water.” From here it is shown that the Holy One, blessed be He, is concerned for Israel's wealth.⁹⁶Numb. R. 19:9. (Ibid., vs. 10:) “So Moses and Aaron gathered the congregation before the rock.” [This verse] teaches that each and every person sees himself as if he were standing at the rock. And similarly it says (in Lev. 8:3), “And assemble the whole congregation at the entrance of the tent of meeting.” And so too when they crossed the Jordan, all of Israel fit in between the two poles of the ark, as stated (in Josh. 3:9), “And Joshua said to the Children of Israel, ‘Come closer and listen to the words of the Lord your God.” And it is [also] written (in Josh. 8:33), “All Israel [...] stood on either side of the ark.” Here also all Israel was standing and seeing the miracles which happened at the rock [in front of them]. They began to say, “Moses knows the natural properties of rock. If he wants, he will bring forth water out of this [other] one.” Moses found himself confronted with a dilemma: If he would listen to them, he would disregard the words of the Omnipresent; and the Holy One, blessed be He, (according to Job 5:13) “Catches the wise in their own cunning.” As for the whole of these forty years Moses had been keeping himself from becoming angry with them, because he was afraid of the oath that the Holy One, blessed be He, had sworn (in Deut. 1:35), “Not one of these people from this evil generation shall see [the good land].” They said to him, “Here is a rock. Just as you wish to bring [water] from another rock, you should bring it from this one.” He gave a command to them (in Numb. 20:10), “Please listen, you rebels, shall we bring forth [water for you] from this rock.” What is the meaning of “hamorim (rebels)?” There are many understandings of it. Hamorim is rebels; hamorim is fools, as in the islands of the sea they call fools, morim. Some say hamorim are those that [inappropriately] instruct their teachers. Hamorim [can also be] arrows, as stated (in I Sam 31:3), “and some of the arrows (morim) struck him, men with bows.” (Numb. 20:11:) “Then Moses raised his hand and struck.” [When] he struck one time, the rock began dribbling a little water, as stated (in Ps. 78:20), “See, he struck a rock, and water trickled out (yazuvu),” like a person with a discharge (zav), in that it dribbles [in] drops. They said to him, “Son of Amram, is this water for nursing children or for babes weaned from milk?” Immediately, he became angry with them, struck it (according to Numb. 20:11) “twice [with his rod], and a lot of water came forth.” Yet for all that, Moses only made [water] from the rock that the Holy One, blessed be He, had told him. And how do we see that they also brought out water from the rock that Israel had said to him and every rock and stone that was in that place? It is so stated (in Ps. 78:15), “He split rocks in the desert.” Moshe already had his [sin] in his hand; because [the Children of Israel] were silent and did not sing praise, they were [also] caught.

(Lev. 8:3:) “And assemble the whole congregation.” The Holy One, blessed be He, said to Moses, “Pay him honor in front of all Israel, in order that they may see him today when he enters the high priesthood. [In addition,] you are to warn them not to rebel against the priesthood like Korah and his crowd (in Numb. 16:1-35). For I know that Uzziah is going to arise and rebel against the priesthood (in II Chron. 26:16-21).” Thus it is stated (in Numb. 17:5), “It was to be a reminder to the Children of Israel that no outsider [who was not of Aaron's seed] should draw near [to offer incense before the Lord].” He (i.e., Uzziah) was not of Levi's seed, as Korah was [of Levi's seed], and not of Aaron’s seed. Immediately (in II Chron. 26:19), “Uzziah, holding the censer and ready to burn incense, got angry; but as he got angry with the priests, leprosy broke out on his forehead.” [So Moshe] said to [God], “According to the judgement that You did to Korah You would do to him?” He said to him, “No, (Numb. 17:5, cont.), ‘let him not be like Korah and his crowd.’” He said to Him, “And how do You act toward him?” He said to him (ibid., cont.), “as the Lord spoke to him through Moses.” [So] he said to Him, “And what is that?” He (the Holy One, blessed be He,) said to him (Moses), “Just as I did to your hand (in Exod. 4:6), ‘and when he withdrew it, behold it was leprous, (as white) as snow’; so will I do to him.” Therefore (in Lev. 8:3), “And assemble the whole congregation”.