Bamidbar 16:3
They combined against Moses and Aaron and said to them, “You have gone too far! For all the community are holy, all of them, and the LORD is in their midst. Why then do you raise yourselves above the LORD’s congregation?”
Bamidbar 16:28-30
And Moses said, “By this you shall know that it was the LORD who sent me to do all these things; that they are not of my own devising: if these men die as all men do, if their lot be the common fate of all mankind, it was not the LORD who sent me. But if the LORD brings something unheard of, so that the ground opens its mouth and swallows them up with all that belongs to them, and they go down alive into Sheol, you shall know that these men have spurned the LORD.”
Sforno
for they do not deserve to even be buried together with the remainder of the people.
Nedarim 39b:3
Rava interpreted: … Here, Moses is saying: If Gehenna is already a creation and exists, well and good; if not, God should create it now.
Midrash Tanchuma Buber, Korach 27:1
It was taught in the name of our master: A place was set aside for them [the sons of Korach] in Gehinnom where they sat and chanted. Rabbah bar bar [sic] Hanah said: One time it happened that we were traveling on a road, when an Arab merchant said to me: Come, I will show you chasms of Korah. I went and saw two fissures out of which was coming smoke. He took a ball of clipped wool, steeped it in water, placed it on a spearhead, and raised it over them. Then he said to me: Listen, what do you hear. I actually heard them saying: Moses and his Torah represent truth, but they (Korah and his companions) are liars. So in the world to come the Holy One is going to take them out of Gehinnom. Moreover, it is with reference to them that Hannah said (in I Sam. 2:6): The Lord brings death and gives life; He brings down to Sheol and raises up.
Rabbi Adin Steinsaltz
Moses calls for something that is beyond the natural order to intervene in the dispute and decide it. What exactly is Moses so angry about?
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The disputes until now have always been with outsiders … Korach, however, is not an outsider … It is a feeling of desperation and realization that one cannot rely on anyone. … The Levites are not just Moses’ tribe; they are also his loyalists.
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the claims put forward by Korach … are much more far-reaching than any other claim advanced against him thus far. … the complaints, for the first time, do not relate to a practical problem but to a fundamental religious question. Korach says, in essence, that Moses is certainly a great man – he does not deny this – but that Moses also adds his own content to God’s will. … Moses’ argument with these people relates to the way in which God chooses to reveal Himself and communicate with people. … [In previous disputes] they were not about [Moses] as an individual but about God and His anointed. … Korach and his party are basically like the original Reform Jews who say that they are for God, for the Torah, and for the Sanctuary, but not for any of the “later additions.” … [The issue is} Faith in Moses as God’s prophet is fundamental to our faith … the Shekhina speaks from his throat. … Here, in the case of Korach and his followers, there is an attempt to separate between God and Moses. … such a separation undermines the people’s ability to continue receiving the Torah — both regarding the Written Law and the Oral Law. … [In this case, Korach is] making logical arguments regarding basic tenets of our faith.
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Korach and his followers use Moses’ own words against him. … In essence, [they] reminded Moses that he wanted people who would be more involved – he wanted prophets. Here were 250 people, all of whom were volunteering to fill these roles. … The rebels demand that the priesthood be opened to everyone as well. … There is much to be said, them, for Korach’s demand to open the priesthood class. Underlying a person’s desire to be a Priest, then is not just a desire for honor but a true desire to express oneself in the realm of holiness. … They argue that instead of forming a structure where the Priest does everything and there is no room for individual expression, it is possible to bring in other people as well …
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Moses simply does not believe that these people are acting for the sake of Heaven. … [In] his view of the dispute … it is dishonest … behind its stated claims lurk other motives. … according to the Midrash, behind the facade of this great man lurked a personal grudge. … People often use slogans of holiness, but what lies behind these slogans is often nothing but personal pettiness. Even when all slogans are for the good of the party, or for the good of the world, one should still search for what lies beneath them, below the surface. Sometimes one finds there a small, frustrated person who wanted to receive something and did not get it. … For hatred caused by envy, gracious gestures by the other side will never help, because the source of the hatred is not an act of injustice, but a deep-seated feeling of jealousy. … There is no remedy for such hatred, and because of this, Moses needed to eradicate them completely.
Rabbi Yehudah Leib
This world is in fact called the “world of separation,” one where each creature looks out for itself. That is why it is “all strife.” But Israel attains peace and wholeness by means of Torah. Whoever truly serves God properly, in order that God’s will be fulfilled in the world, and acts only for the sake of heaven, can be jealous of no person. What is any single human being that his deeds should be accepted above? It is only through the entire community of Israel that God’s will is fulfilled in the world. So everyone has to give his portion thoroughly over to the community. Once you do that, you see that there is no difference between you and your fellow. This was the quality of Aaron … But of Korach, it says: “He took” — for himself. And even the very greatest person, when he is just for himself, what is he?