Moses
Numbers 16:19ESV·traditional attribution

Then Korah assembled all the congregation against them at the entrance of the tent of meeting. And the glory of the LORD appeared to all the congregation.

Matthew Henry Presbyterian @wholebiblehenry

Here is, I. The insolence of Dathan and Abiram, and their treasonable remonstrance. Moses had heard what Korah had to say, and had answered it; now he summons Dathan and Abiram to bring in their complaints (Num 16:12); but they would not obey his summons, either because they could not for shame say that to his face which they were resolved to say, and then...

Commenting on Numbers 16:12-22

John Gill Reformed Baptist @doctorgill

And Korah gathered all the congregation against them,.... Not his own company only, but as many of the whole congregation of Israel as he could get together, and especially the principal men; so that it seems there was a, general prevailing inclination in the people to take part with him against Moses and Aaron, who wished him success in his undertaking, and readily came together...

Geneva Bible Notes Reformed @genevanotes

And Korah gathered all the congregation against them unto the door of the tabernacle of the congregation: and the glory of the LORD appeared unto all the congregation. (l) All that were of their faction.