Bamidbar 16:1-3
Now Korah, son of Izhar son of Kohath son of Levi, betook himself, along with Dathan and Abiram sons of Eliab, and On, son of Peleth–descendants of Reuben–to rise up against Moses, together with two hundred and fifty Israelites, chieftans of the community, chosen in the assembly, men of repute. 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?”

Rashi
But Korah who certainly was a clever (lit. open-eyed) man, what reason had he to commit this folly? His mind’s eye misled him. He saw by prophetic vision a line of great men descending from him [referring to Samuel and other descendants] … He said, “Is it possible that all this dignity is to arise from me and I shall remain silent (be myself of no importance)?”

Rambam
Jealousy, desire, and love of honor take a person out of the world. The reason for this is that possessing these three middos, or even a single one of them, inevitably causes a person to forfeit his emunas haTorah.

Rabbi Shlomo Wolbe
This incident gives us an understanding of the hidden motivations that underlie our actions. Korach’s fight against Moshe stemmed from his feelings of jealousy, which generated his ideology regarding the mitzvos in general and the leader of the nation in particular. Additionally, he solidified his position with the prophetic vision of a great future. These three factors led Korach to take action against Moshe: 1) he had a philosophy; 2) he even had “proof” that he was right; yet 3) it was all rooted in a negative trait — jealousy. The same three factors often compel us to act, as well. We might have ideas and ideals, and we might even have proof that we are following the correct path, but we must always realize that these ideas or actions are borne of our character traits. Before acting, and certainly before taking drastic measures, we should take time to think about the real impetus for our thoughts and deeds. If they are rooted in positive traits — kindness, compassion, and so on — then we know we are truly on the right path. However, if we suspect that they might be rooted in negative traits — jealousy, hatred, craving for honor, and the like — then we are better off admitting our faults and refraining from acting on them.

…
In fact, a person must be especially careful when he acts “for the sake of Heaven,” because he might think that the truth of his cause gives him license to do as he pleases.

Can you think of examples of bad behavior that were rationalized? Why are religious conflicts particularly dangerous in this regard?

How do you develop the insight to recognize your own rationalizations? Do you have to do it all by yourself?

Ein Yaakov (A compilation of midrashic material from the Talmud)
On, who repented upon his sin and withdrew from Korah. … Rab said: “On ben Peleth was saved by his wife [from being among the congregation of Korah]. She said to him: “What is the difference to you? If Moses will be master, you are only disciple, and you will be in the same position if Korah will be the master.” And to his answer: “What shall I do, I was with with them in consultation, and swore to take part with them?” She said, “I know that the whole congregation is holy, as it is written (Bamidbar 16:3) For the whole of the congregation are all of them holy, remain in your house and I will save thee.” She made him drink wine to intoxication, and she made him sleep in the house, and she herself sat outside at the entrance of the house, uncovered her head, loosened her hair, and whoever came to his house, to call upon On, when he saw the uncovered head of the woman, returned. … And this is meant by the passage (Proverbs 14:1) “The wise among women builds her house — referring to the wife of On ben Peleth.”

Rabbi Henach Leibowitz
If On was completely persuaded by the yetzer hara, how could his wife so easily pull him away from the machlokes [conflict]? The yetzer hara is convincing, but truth — emet — is even more powerful. Was it so easy? Why did On’s wife have to go through so many elaborate steps to prevent from participating in the rebellion?

Hai Gaon, circa 11th century, Responsa 13, The Parable of the Fox and the Lion, a midrash on Korach, cited by Rabbi Dessler
There is a parable about a lion who wanted to eat a fox for dinner. The fox said to the lion: “What good can I be to you? I will show you a very fat human being whom you can kill and you’ll have plenty to eat.” There was a pit covered with branches and grass and behind it sat a man. When the lion saw the man, he said to the fox: “I’m afraid this man may pray and cause me trouble.” The fox said: “Nothing will happen to you or to your son. Maybe your grandson will have to suffer for it. Meanwhile you can eat and be satisfied; until your grandson comes along, there is still plenty of time.” The lion was persuaded and ran towards the man. He fell into the pit and thus was trapped. The fox came to the edge of the pit and looked down. The lion said, “Didn’t you tell me that the punishment would only come upon my grandson?” “Your grandfather may have done something wrong and you are suffering for it,” replied the fox. “Is that fair?” asked the lion. “The father eats sour grapes and the children’s teeth ache?” “So why didn’t you think of that before?” replied the fox. How much mussar there is in this fable!

Rabbi Dessler presents this parable as a profound midrash on Korach, and asks us to seek its meaning. What do you think it means?