And Moses and Aaron went into the tent of meeting, and when they came out they blessed the people, and the glory of the LORD appeared to all the people.
23. And Moses and Aaron went into the tabernacle This is a repetition of the same statement, except that what had been said of Aaron only is now also ascribed to Moses, i.e., that he blessed the people, but for a different reason, for although he was God’s prophet, yet Aaron, in right of his office, was the only mediator.
We are not told what Moses and Aaron went into the tabernacle to do, Lev 9:23. Some of the Jewish writers say, "They went in to pray for the appearance of the divine glory;" most probably they went in that Moses might instruct Aaron how to do the service that was to be done there - burn incense, light the lamps, set the show-bread, etc....
Commenting on Leviticus 9:23-24
And there came a fire out from before the Lord,.... Either from heaven, or from the holy of holies, where was the symbol of the divine Presence, and Jehovah had now took up his residence: and consumed upon the altar the burnt offering, and the fat; according to Aben Ezra, the burnt offering of Aaron, and of the people, and of the daily sacrifice, for...