When Moses entered the Tent of Meeting to speak with the LORD, he heard the voice speaking to him from between the two cherubim above the mercy seat on the ark of the Testimony. Thus the LORD spoke to him.
89. And when Moses was gone into the tabernacle There seems at first sight to be a kind of contradiction between this passage and the other, in which we saw that a thick cloud stood in the door of the tabernacle, so that Moses could not enter it.
We have here an account of the great solemnity of dedicating the altars, both that of burnt-offerings and that of incense; they had been sanctified before, when they were anointed (Lev 8:10, Lev 8:11), but now they were handselled, as it were, by the princes, with their free-will offerings.
Commenting on Numbers 7:10-89
And when Moses was gone into the tabernacle of the congregation to speak with him--As a king gives private audience to his minister, so special license was granted to Moses, who, though not a priest, was admitted into the sanctuary to receive instructions from his heavenly King as occasion demanded.