Moses
Numbers 16:47ESV·traditional attribution

So Aaron took it as Moses said and ran into the midst of the assembly. And behold, the plague had already begun among the people. And he put on the incense and made atonement for the people.

Matthew Henry Presbyterian @wholebiblehenry

Here is, I. A new rebellion raised the very next day against Moses and Aaron. Be astonished, O heavens, at this, and wonder, O earth! Was there ever such an instance of the incurable corruption of sinners? On the morrow (Num 16:41) the body of the people mutinied. 1. Though they were so lately terrified by the sight of the punishment of the rebels.

Commenting on Numbers 16:41-50

John Gill Reformed Baptist @doctorgill

And he stood between the dead and the living,.... The plague beginning at one end of the camp, and so proceeded on, Aaron placed himself between that part of it wherein it had made havoc, and that wherein yet it was not come; the Targum of Jonathan is,"he stood in prayer in the middle, and made a partition, with his censer, between the dead and...

Geneva Bible Notes Reformed @genevanotes

And Aaron took as Moses commanded, and ran into the midst of the congregation; and, behold, the plague was begun among the people: and he put on incense, and made an atonement for the people. (s) God had begun to punish the people.