Musar על בראשית 4:10

it is well known that Kabbalists have said that Korach was the re-incarnation (גלגול) of Cain. Cain had to undergo three גלגולים, one each for his נפש, his רוח, and his נשמה. They were the Egyptian whom Moses had slain; Yitro, Moses' father-in-law,as alluded to in Judges 4,17. In that verse Yael is described as the wife of Chever Hakeyni, the word "Hakeyni" being a reference to her being descended from Cain." He reappeared in the guise of Korach. Moses, on the other hand, was a re-incarnation of Abel whom Cain had killed. Moses took revenge on behalf of Abel on three separate occasions. 1) When he killed the Egytian who was the re-incarnation of Cain's נפש. This is hinted at in the wording ויך את המצרי. The numerical value of ויך, when you add one digit for the word itself, equals the numerical value of הבל, i.e. 37. The word המצרי, equals the numerical value of משה, i.e. 345. 2) Yitro deferred to Moses by giving him his daughter Tzipporah as a wife. She was the (גלגול) of the extra twin that had been born with Abel, on whose account Cain had slain Abel out of jealousy. When Korach now started a quarrel he simply reverted to the pattern in which his original ancestor Cain had acted. 3) Moses then killed him (i.e. caused his death), fulfilling the Torah's commandment that if someone has shed innocent blood, his own blood will be spilled by human hand (Genesis 9,6). We must understand that verse as telling us that the very person who had been slain, will in due course slay his murderer. This is why we find Moses, who was in reality the re-incarnation of Abel, slaying Korach who was the re-incarnation of Cain. The fact that Korach's death was due to the earth swallowing him was also an example of the punishment fitting the crime, since the same earth had been remiss when it opened to hide the evil deed that Cain had committed, and "covered" his blood (compare Genesis 4, 10/11). All this is explained by the Tziyoni.