Kabbalah zu Bamidbar 26:9

"And Moses was much angered,"because Korah and his company refused to acknowledge him and did not allow him to settle the dispute. It is written "much," because they denied the acknowledgment of the work of Creation. So Korah denied 1. Korah denied everything above in Zeir Anpin and below in the souls, as it is written: "When they strove against Hashem" (Numbers 26:9) which is the secret of Zeir Anpin, for the damage that he did reached both above to Zeir Anpin and below to Moses. Therefore, Korah cleaved on to what he deserved; he reached Gehenom, as written, "They went down alive into Sheol" (Numbers 16:33).