Exodus 40:35

And Moses was not able to enter into the tent of the
congregation
He had been there before, both in the holy, and in the most holy place, to see that the furniture of each were put as the Lord directed, which being done he came out again; and now a cloud being on the outside of it, and the glory of the Lord within, he was so struck with an awe and reverence of the divine Being, of whose presence these were a symbol, that he could not engage his heart, or had not boldness to go into the tabernacle until he was called, ( Leviticus 1:1 ) for so it follows:

because the cloud abode thereon, and the glory of the Lord filled
the tabernacle;
there was something, no doubt, very venerable in the spreading cloud, as well as very striking in the refulgent glory, which commanded distance, even to a person that had been used to converse with God; Moses, that went into the midst of the cloud where the Lord was, now could not or durst not go into the tabernacle it covered; and he who then was not deterred by the sight of the glory of God, which was like devouring fire, ( Exodus 24:16-18 ) now could not, or at least thought it not proper and advisable to enter into the holy place erected for the service and worship of God; the chief reason of which may be, because, as yet, he had not a call to enter, as he then had, and as we find was afterwards given him, ( Leviticus 1:1 ) and perhaps another reason may be, because he was now no longer a priest; Aaron and his sons being invested with the priestly office, whose business it was to draw nigh to God; and indeed the call he afterwards had was not to come into the tabernacle, but was a call unto him out of it.