A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
num 16:1THE REBELLION OF KORAH. (Num. 16:1-30)
Now Korah, the son of Izhar--Izhar, brother of Amram (Exo 6:18), was the second son of Kohath, and for some reason unrecorded he had been supplanted by a descendant of the fourth son of Kohath, who was appointed prince or chief of the Kohathites (Num 3:30). Discontent with the preferment over him of a younger relative was probably the originating cause of this seditious movement on the part of Korah.
Dathan and Abiram, . . . and On--These were confederate leaders in the rebellion, but On seems to have afterwards withdrawn from the conspiracy [compare Num 16:12, Num 16:24-25, Num 16:27; Num 26:9; Deu 11:6; Psa 106:17].
took men--The latter mentioned individuals, being all sons of Reuben, the eldest of Jacob's family, had been stimulated to this insurrection on the pretext that Moses had, by an arbitrary arrangement, taken away the right of primogeniture, which had vested the hereditary dignity of the priesthood in the first-born of every family, with a view of transferring the hereditary exercise of the sacred functions to a particular branch of his own house; and that this gross instance of partiality to his own relations, to the permanent detriment of others, was a sufficient ground for refusing allegiance to his government. In addition to this grievance, another cause of jealousy and dissatisfaction that rankled in the breasts of the Reubenites was the advancement of Judah to the leadership among the tribes. These malcontents had been incited by the artful representations of Korah (Jde 1:11), with whom the position of their camp on the south side afforded them facilities of frequent intercourse. In addition to his feeling of personal wrongs, Korah participated in their desire (if he did not originate the attempt) to recover their lost rights of primogeniture. When the conspiracy was ripe, they openly and boldly declared its object, and at the head of two hundred fifty princes, charged Moses with an ambitious and unwarrantable usurpation of authority, especially in the appropriation of the priesthood, for they disputed the claim of Aaron also to pre-eminence [Num 16:3].
num 16:3they gathered themselves together against Moses and against Aaron--The assemblage seems to have been composed of the whole band of conspirators; and they grounded their complaint on the fact that the whole people, being separated to the divine service (Exo 19:6), were equally qualified to present offerings on the altar, and that God, being graciously, present among them by the tabernacle and the cloud, evinced His readiness to receive sacrifices from the hand of any others as well as from theirs.
num 16:4when Moses heard it, he fell upon his face--This attitude of prostration indicated not only his humble and earnest desire that God would interpose to free him from the false and odious imputation, but also his strong sense of the daring sin involved in this proceeding. Whatever feelings may be entertained respecting Aaron, who had formerly headed a sedition himself [Num 12:1], it is impossible not to sympathize with Moses in this difficult emergency. But he was a devout man, and the prudential course he adopted was probably the dictate of that heavenly wisdom with which, in answer to his prayers, he was endowed.
num 16:5he spake unto Korah and unto all his company--They were first addressed, not only because they were a party headed by his own cousin and Moses might hope to have more influence in that quarter, but because they were stationed near the tabernacle; and especially because an expostulation was the more weighty coming from him who was a Levite himself, and who was excluded along with his family from the priesthood. But to bring the matter to an issue, he proposed a test which would afford a decisive evidence of the divine appointment.
Even to-morrow--literally, "in the morning," the usual time of meeting in the East for the settlement of public affairs.
the Lord will show who are his, . . . even him whom he hath chosen will he cause to come near unto him--that is, will bear attestation to his ministry by some visible or miraculous token of His approval.
num 16:6Take your censers, Korah, and all his company, &c.--that is, since you aspire to the priesthood, then go, perform the highest function of the office--that of offering incense; and if you are accepted well. How magnanimous the conduct of Moses, who was now as willing that God's people should be priests, as formerly that they should be prophets (Num 11:29). But he warned them that they were making a perilous experiment.
num 16:12Moses sent to call Dathan and Abiram--in a separate interview, the ground of their mutiny being different; for while Korah murmured against the exclusive appropriation of the priesthood to Aaron and his family, they were opposed to the supremacy of Moses in civil power. They refused to obey the summons; and their refusal was grounded on the plausible pretext that their stay in the desert was prolonged for some secret and selfish purposes of the leader, who was conducting them like blind men wherever it suited him.
num 16:15Moses was very wroth--Though the meekest of all men [Num 12:3], he could not restrain his indignation at these unjust and groundless charges; and the highly excited state of his feeling was evinced by the utterance of a brief exclamation in the mixed form of a prayer and an impassioned assertion of his integrity. (Compare Sa1 12:3).
and said unto the Lord, Respect not thou their offering--He calls it their offering, because, though it was to be offered by Korah and his Levitical associates, it was the united appeal of all the mutineers for deciding the contested claims of Moses and Aaron.
num 16:16Moses said unto Korah, Be thou and all thy company before the Lord--that is, at "the door of the tabernacle" (Num 16:18), that the assembled people might witness the experiment and be properly impressed by the issue.
num 16:17two hundred fifty censers--probably the small platters, common in Egyptian families, where incense was offered to household deities and which had been among the precious things borrowed at their departure [Exo 12:35-36].
num 16:20the Lord spake unto Moses and Aaron, saying, Separate yourselves from among this congregation--Curiosity to witness the exciting spectacle attracted a vast concourse of the people, and it would seem that the popular mind had been incited to evil by the clamors of the mutineers against Moses and Aaron. There was something in their behavior very offensive to God; for after His glory had appeared--as at the installation of Aaron (Lev 9:23), so now for his confirmation in the sacred office--He bade Moses and Aaron withdraw from the assembly "that He might consume them in a moment."
num 16:22they fell upon their faces, and said, O God, the God of the spirits of all flesh--The benevolent importunity of their prayer was the more remarkable that the intercession was made for their enemies.
num 16:24Speak unto the congregation, . . . Get you up from about the tabernacle--Moses was attended in the execution of this mission by the elders. The united and urgent entreaties of so many dignified personages produced the desired effect of convincing the people of their crime, and of withdrawing them from the company of men who were doomed to destruction, lest, being partakers of their sins, they should perish along with them.
num 16:27the tabernacle of Korah, Dathan, and Abiram--Korah being a Kohathite, his tent could not have been in the Reubenite camp, and it does not appear that he himself was on the spot where Dathan and Abiram stood with their families. Their attitude of defiance indicated their daring and impenitent character, equally regardless of God and man.
num 16:28Moses said, Hereby ye shall know that the Lord hath sent me to do all these works--The awful catastrophe of the earthquake which, as predicted by Moses, swallowed up those impious rebels in a living tomb, gave the divine attestation to the mission of Moses and struck the spectators with solemn awe.
num 16:35there came out a fire from the Lord--that is, from the cloud. This seems to describe the destruction of Korah and those Levites who with him aspired to the functions of the priesthood. (See Num 26:11, Num 26:58; Ch1 6:22, Ch1 6:37).
num 16:37Speak unto Eleazar--He was selected lest the high priest might contract defilement from going among the dead carcasses.
num 16:39the brazen censers . . . made broad plates to be a memorial--The altar of burnt offerings, being made of wood and covered with brass, this additional covering of broad plates not only rendered it doubly secure against the fire, but served as a warning beacon to deter all from future invasions of the priesthood.
num 16:41the children of Israel murmured against Moses and against Aaron, saying, Ye have killed the people of the Lord--What a strange exhibition of popular prejudice and passion--to blame the leaders for saving the rebels! Yet Moses and Aaron interceded for the people--the high priest perilling his own life in doing good to that perverse race.
num 16:48he stood between the living and the dead--The plague seems to have begun in the extremities of the camp. Aaron, in this remarkable act, was a type of Christ.