Or HaChaim on Numbers 26:9/אור החיים על במדבר כ״ו:ט׳

1 הוא דתן ואבירם, "the same Datan and Aviram, etc." What did the Torah want to teach us by referring to Datan and Aviram at this point? If the Torah merely wanted to tell us that these two were the same Datan and Aviram we have encountered in connection with the rebellion of Korach, we knew this. It was hardly likely that two members of the tribe of Reuven both named Eliav each had two sons called Datan and Aviram. Moreover, their names did not need to appear here at all. None of the other families who had died before this census were mentioned in this sequence. Furthermore, why was the Torah so long-winded in telling us how these two brothers "incited in the company of Korach against Moses and Aaron when they incited against G'd?"

2I believe that the reason the Torah recalls what these brothers had done was to inform us that they had been the cause of Korach's rebellion. It was G'd's wish to publicise the names of the wicked people who had orchestrated the evil in question. By writing אשר הצו, the Torah stresses that these two incited others both against Moses and Aaron as well as against G'd. Rashi explains the verse in the same sense. Once we have heard that these two caused the whole Israelite community to sin, it is quite possible to blame them also for having incited Korach. Although the Torah wrote (Numbers 16,1) "Korach took, etc.," which sounds as if Korach had initiated whatever he did, this may have occurred after something the brothers Datan and Aviram had already done, and that they had incited him. When the Torah repeats here once more what it had written in Numbers 16,32 that "the earth opened its mouth and it swallowed them and Korach," it may be that these two were the root cause why Korach and family were swallowed by the earth and why the 250 men who offered incense were burned to death at the time. The Torah also suggests here that but for the two demagogues Datan and Aviram the Israelites who had gathered threateningly against Moses and Aaron would have done תשובה.

3The best proof for our theory is the fact that Moses is described as trying to placate only Datan and Aviram when he sent messengers to call them for a chat (Numbers 16,12). When they refused to come, Moses even went to look them up (16,25). The reason was that Moses felt that these two were at the bottom of the whole rebellion. Once we accept this, the death of all the people who perished can be attributed to Datan and Aviram. This results in our being able to find some excuse for both Korach and the 250 men who offered the incense. You find that the Torah wrote in Deut.11,6: "and what He has done to Datan and Aviram, the sons of Eliav, how the earth opened its mouth and swallowed them, their houses, and their tents and every living thing which followed them." Moses attributed the entire debacle exclusively to Datan and Aviram. Having explained this, we can now understand the scholar in Sanhedrin 110 who holds that the company of Korach does not qualify for life in the hereafter as referring only to Datan and Aviram. The contrary opinion who holds that Korach and company will enjoy life in the hereafter and who base themselves on Samuel I 2,8 that "G'd lowers people to Sheol and brings them up again," must be understood as referring to Korach and companions exclusive of Datan and Aviram to whom the verse does not apply.