Likutei Moharan 10:9/ליקוטי מוהר"ן י׳:ט׳

19. This is the explanation:

2Rabbah bar bar Chanah recounted: This merchant said to me, “Come, I will show you those swallowed up with Korach.” I went and saw two cracks from which fumes were coming out. [The merchant] took a ball of omra (wool) and washed it in water. Then he put it on the head of his romach (spear) and inserted it there. When he removed it, it was ichrakh (scorched) entirely. He said to me, “Listen! What do you hear?” I heard them saying,

3“Moshe and his Torah are true, and we are false .” [The merchant] said to me, “Once every thirty days Hell brings them back to here, like meat in a pot. And this is what they say, that Moshe and his Torah are true and they are false” (Bava Batra 74a).

4those swallowed up with Korach — As we find in the Midrash: Korach was a heretic (Bamidbar Rabbah 18). And heresy is similar to idol worship. I saw two cracks from which fumes were coming out — This alludes to the Divine anger brought on by heresy. As our Sages taught: As long as there is idol worship in the world, there is Divine anger in the world. The two cracks correspond to the two nostrils from which smoke emanates, as in (Psalms 18:9), “Smoke went up out of his nostrils.”

5took a ball of OMRa (wool) — This is synonymous with the OMeR, as mentioned above. [It refers to Mordekhai/revealed Torah/hands, which is joined with hidden Torah, as in:]

6washed it in water — This is the se’orim (barley), which corresponds to “The Book of Esther was dictated with ruach-of-holiness”/the feet. This is because the feet are the “water brooks” (Psalms 42:2), in that they correspond to willows of the stream. As our Sages taught: A person’s feet are arvin (guarantors) for him (Sukkah 53a). ARVin corresponds to ARVey (willows) of the stream, the “water brooks.” [Thus the wool in water] alludes to Mordekhai and Esther/the hands and the feet/clapping and dancing.

7Then he put it on the head of his romach (spear) — RoMaCh is RuaCh Mem (cf. Zohar III, 237a), as in, “Come from the four RuChot (winds), O spirit.” This is because the mem refers to the four winds, which corresponds to the ruach of the tzaddik that “blows in the arms and the legs.” And the head of the romach is the tzaddik from whom the ruach comes, as in, “a man in whom there is <the Lord’s> ruach .”

8When he removed it, it was ichrakh (scorched) entirely — The word iChRaKh has the connotation of life and length of days. As our Sages taught: “The slothful man will not YaChaRoKh (roast) his catch” (Proverbs 12:27) —he will neither YiChyeh (live) nor YaaRiKh (have length of days) (Eruvin 54b). This is the meaning of scorched entirely: it alludes to life and length of days. By eliminating haughtiness—i.e., idolatry—[one’s] wisdom is as it should be. And with wisdom, a person lives long, as is written (Ecclesiastes 7:12), “Wisdom gives life to those who possess it.”

9He said to me, Listen! What do you hear? I heard them saying, Moshe and his Torah are true — They admitted to the truth. This happens when a person draws closer to the <tzaddik> in order to receive ruach from <him>. As a result, [the spirit of] haughtiness and idolatry are shattered. Then even those [distant from God]—who are from <the Other Side>—recognize the greatness of the Holy One.

10[The merchant] said to me, Once every thirty days Hell brings them back to here…. And this is what they say, that Moshe and his Torah are true — Rashbam explains that this happened every New Moon. This is because everything has its root <Above>, and the root of repentance is the New Moon. As our Sages expounded: On the New Moon, the Holy One says, “Bring an atonement offering on My behalf [for My having caused the moon to be diminished]” (Chullin 60a). This is an aspect of repentance. And on the New Moon, this repentance is projected down [from God] into all of creation. Thus, even Korach and his followers must feel some remorse on the New Moon. But repentance does not help them, because essentially repentance is only in this world. For he who toiled on the eve of Shabbat will eat on Shabbat (Avodah Zarah 3a).

11It follows, certainly, that this confession, the remorse and admission [of Korach and his followers], does not absolve them from the punishment of Hell. This is why Hell brings them back to here. For they are not exempt with this. Even so, there is no [suffering in] Hell on the New Moon as on other days (Zohar II, 150b). Hell on the New Moon is only remorse: feeling sorry, confessing and feeling shame. This itself was their Hell. The language is precise: Hell brings them back to here. In other words, this that they are brought back to here, that they return and admit—this is their Hell.