(Numb. 16:1:) “Now Korah betook himself.” This text is related (to Prov. 18:19), “A brother offended (rt.: psh') is more formidable than a fortified city; [such] contentions are like a castle bar.” The brother offended is Korah, in that he sided against Moses. So he rebelled and sank from whatever glory that he possessed.
Now offended (rt: psh') can only imply rebellion, since it is stated (in II Kings 3:7), “The king of Moab has rebelled (psh') against me.” It also says (in II Kings 8:22), “then did Libnah rebel (rt.: psh').” (Prov. 18:19:) “[Such] contentions are like a castle bar.” [The earth raised its bars against him like a castle.] (Prov. 18:19:) “Like a castle bar.” [These words also refer to Korah,] who sided against Moses and against the Omnipresent. (Numb. 16:1:) “[Now Korah …] took.” “Took” can only be a word for "attracting with persuasive words," in that he attracted all the leaders of Israel and the sanhedraot [to follow] after him. Concerning Moses it is written (in Numb. 1:17), “So Moses and Aaron took these men.” And similarly it is written (in Numb. 8:2), “Take Aaron and his sons with him.” And so does it say (in Hos. 14:3), “Take words with you and repent….” And so does it [also] say (in Genesis 12:15), “and the woman was taken to the house of Pharaoh.”
Ergo (in Numb. 16:1) “Now Korah […] took,” in that he drew (i.e., took) their hearts with persuasive words. (Numb. 16:1:) “Now Korah […] betook himself.” Because of what did he dissent? Because of Elizaphan, the son of his father's brother, who had been appointed prince (nasi) over his clan. So it says (in Numb. 3:30), “And the prince of the ancestral house for the Kohathite clan was Elizaphan ben Uzziel.”
Korah said, “Father had four brothers.” It is so stated (according to Exod. 6:18), “And the sons of Kohath were Amram, Izhar, Hebron, and Uzziel.” “As for Amram, the first-born; his son Aaron and his sons attained the high priesthood, and his brother Moses [attained] the kingship. So who deserves to get second [place]?
Should it not be the second [son]? Now I am Izhar's son. I deserved to be prince of my clan, but he has appointed the son of Uzziel. Should the youngest of father's brothers become superior to me? See, I am dissenting and declaring everything invalid, whatever he had done.” Therefore, there was dissent.