Charles Ellicott Commentary Numbers 16:1

"Now Korah, the son of Izhar, the son of Kohath, the son of Levi, with Dathan and Abiram, the sons of Eliab, and On, the son of Peleth, sons of Reuben, took [men]:" — Numbers 16:1 (ASV)

Now Korah, the son of Izhar ... — Some suppose that the copula before “Dathan and Abiram” should be omitted, and that the verse should be rendered this way: Now Korah, the son of Izhar, the son of Kohath, the son of Levi, took Dathan and Abiram, etc. The rebellion of Korah, Dathan, and Abiram is the only important event recorded in connection with the protracted wandering in the desert. The time and place of its occurrence cannot be positively determined. The circumstances from which it appears to have arisen make it probable that it took place during one of the early years of the wanderings in the wilderness, either during the stay at Kadesh or after the departure from it.

In favor of the supposition that the occurrence took place during the stay at Kadesh, it may be argued:

1. The history of the Israelites between the first and the second encampments at Kadesh appears to be intentionally regarded and treated as a blank.

2. During that interval, they appear to have been scattered throughout the wilderness, while the narrative of the rebellion of Korah seems to assume the concentration of the people in one place.

The whole of the narrative bears the clear mark of historical truth. The leaders of the rebellion, among whom Korah holds the most conspicuous place (Numbers 26:9; Jude 1:11), belonged to the tribes of Levi and Reuben.

Korah, as the descendant of Izhar, the brother of Amram—who was the father (or, as some maintain, the more distant ancestor) of Moses and Aaron—may well be supposed to have been jealous of the peculiar prerogatives of the priestly family. He may also have been jealous of the leadership of Elizaphan, the son of Uzziel (Numbers 3:30), who appears to have been the youngest son of Kohath, while the name of Izhar stands next to that of Amram (Numbers 3:19).

Dathan and Abiram, moreover, as the sons of Eliab, the son of Pallu, the son of Reuben (Numbers 26:5–9)—who was the eldest son of Jacob—may, for similar reasons, be supposed to have been discontented on account of the transfer of the birthright. They may also have been discontented with the resulting loss of the leadership that had been possessed by their tribe, and which was now held by the tribe of Judah.

It is possible that they may have regarded the priesthood also as among the prerogatives of the firstborn which should have passed to them. The proximity of the Kohathites to the Reubenites—for both were encamped on the south side of the Tabernacle—provided an opportunity for their joint deliberations. It has been inferred by some, from Numbers 16:24-27, that they had erected a tabernacle in rivalry with the Tabernacle of the Congregation. No further mention is made of the name of On, nor is he expressly included in the account of the final punishment.