And Moses said unto Korah, Be thou and all thy company {h} before the LORD, thou, and they, and Aaron, to morrow:

(h) At the door of the tabernacle.

Wesley's Notes

16:16 Before the Lord - Not in the tabernacle, which was not capable of so many persons severally offering incense, but at the door of the tabernacle, where they might offer it by Moses's direction upon this extraordinary occasion. This work could not be done in that place, which alone was allowed for the offering up of incense; not only for its smallness, but also because none but priests might enter to do this work. Here also the people, who were to be instructed by this experiment, might see the proof and success of it.

Jamieson-Fausset-Brown Bible Commentary

16-18. Moses said unto Korah, Be thou and all thy company before the Lord-that is, at "the door of the tabernacle" (Nu 16:18), that the assembled people might witness the experiment and be properly impressed by the issue.

Matthew Henry's Concise Commentary

16:16-22 The same glory of the Lord that appeared to place Aaron in his office at first, Le 9:23, now appeared to confirm him in it; and to confound those who set up against him. Nothing is more terrible to those who are conscious of guilt, than the appearance of the Divine glory. See how dangerous it is to have fellowship with sinners, and to partake with them. Though the people had treacherously deserted them, yet Moses and Aaron approved themselves faithful shepherds of Israel. If others fail in their duty to us, that does not take away the obligations we are under to seek their welfare. Their prayer was a pleading prayer, and it proved a prevailing one.