John Gill Bible Commentary

And Moses said unto Aaron, take a censer,.... Which lay in the tabernacle: and put fire therein from off the altar; the altar of burnt offering, from whence fire only was to be taken for burning incense; and lest Aaron in his hurry should forget to take it from thence, but elsewhere, and offer strange fire as his sons had done, Moses expresses the place from whence he should take it: and put on incense: upon the fire, in the censer, which he was to do when he came into the camp, and not as soon as he took the fire from the altar: the censer with fire in it he carried in one hand, and the incense in the other; and when he was in the midst of the congregation, he put the incense on the fire, and burnt it, as appears from Num 16:47, this was an emblem of prayer, and a figure of the intercession and mediation of Christ, Psa 141:2, and go quickly unto the congregation; the case required haste: and make an atonement for them; which was usually done by the sacrifice of a sin or trespass offering, but now there was no time for that, and therefore incense, which was of quicker dispatch, was used for that purpose instead of it: for there is wrath gone out from the Lord; some token of it, some disease was inflicted, which Moses had information of from the Lord, and therefore expressly says: the plague is begun; a pestilence was sent among the people.