ציטירנדיקער פּירוש אויף במדבר 3:29

“And Korah took” - This matter that was in the wilderness of Sinai, when the firstborns were replaced and the Levites were separated,
For the Israelites thought that Moshe our Leader did it according to his own thought, to give greatness to his brother, and also to the sons of Kehat for they are close to him, and all of the Levites that they are his family.
And the Levites conspired against him because they were given to Aaron and his sons.
Datan and Aviram conspired because the firstborn privilege was removed from Reuven their father and given to Yosef; perhaps they suspected that [Moshe did that] for the sake of Yehoshua his servant [who was from Yosef].
Also Korah was a first born, for thus was written.
>And those Heads of the Congregation (edah) were firstborns and they were bringing the olah offerings.
And the proof for this explanation is the miracle of the staff (Bamidbar 17:16-26) that all of Israel saw that Hashem chose the tribe of Levi in place of the firstborns, and therefore it is written (Bamidbar 17:25) “their mutterings ceased,” for the mutterings were about this.
Also Moshe said that “it is not from my own mind” (Bamidbar 26:28), because they suspected that it was from his own mind that he did it.
And further proof is “Hashem did not send me” - for this task - because all the Israelites already believed in him [in general]. Another total proof is “all the congregation are holy” and this is a hint to the firstborns that they are holy, because it is written (shemot 13:2) “sanctify to Me every first born” and they are the priests (Kohanim) that approach Hashem and they are the essence of the whole congregation.

ודתן ואבירם AND DATHAN AND ABIRAM — Because the tribe of Reuben had their place, when they encamped, in the South, thus being neighbours of Kohath and his sons, who, too, encamped in the South (cf. Numbers 3:29), they (the Reubenites) joined Korah in his quarrel. “Woe to the wicked, woe to his neighbour!” — And what induced Korah to quarrel with Moses? He was envious of the princely dignity held by Elzaphan the son of Uziel (Midrash Tanchuma, Korach 1) whom Moses had appointed prince over the sons of Kohath although this was by the express command of God (Numbers 3:30). Korah argued thus: “My father and his brothers were four in number — as it is said, (Exodus 6:18) “and the sons of Kohath were [Amram and Izhar and Hebron and Uziel]”. — “As to Amram, the eldest, his two sons have themselves assumed high dignity, one as king and the other as High Priest; who is entitled to receive the second (the rank next to it)? Is it not “I” who am the son of Izhar, who was the second to Amram amongst the brothers? And yet he has appointed as prince the son of his (Amram’s) brother who was the youngest of all of them! I hereby protest against him and will undo his decision”. — What did he do? He arose and assembled 250 men, fitted to be heads of the Sanhedrin, most of them of the tribe of Reuben who were his neighbours, viz., Elizur the son of Shedeur, (the prince of the tribe of Reuben; cf. Numbers 1:5), and his colleagues, and others of a similar standing, — for here it states (v. 2) that they were “princes of the congregation, those who were called to the assembly (קראי מועד)”, and there (in another passage) it states, (Numbers 1:16) “these were they who were called to the congregation (קרואי העדה)” (amongst whom was also Elizur the son of Shedeur; cf. Numbers 1:5 and Rashi on Numbers 1:16), — and he attired them in robes of pure purple wool. They then came and stood before Moses and said to him, “Is a garment that is entirely of purple subject to the law of Zizith or is it exempt”? He replied to them: “It is subject to that law”. Whereupon they began to jeer at him: “Is this possible? A robe of any different coloured material, one thread of purple attached to it exempts it, and this that is entirely of purple should it not exempt itself (i.e. ipso facto be exempt) from the law of “Zizith”? (Midrash Tanchuma, Korach 2).

Five on the right and five on the left. It is impossible to say five were on the right side of the entrance and five were on the left of the entrance, if so, we find a candlestick on the north [side] and the Torah states, “on the south side of the Tabernacle.”⁶⁵Bamidbar 3:29. The verse quoted by Rashi describes the location where the Kehas family encamped. It is not stated in reference to the candlestick. See Shemos 26:35 and 40:24 for the location of the candlestick. Therefore, Moshe’s [candlestick] was in the middle, five [candlesticks] on its right and five on its left.