Charles Ellicott Commentary Exodus 40:35

"And Moses was not able to enter into the tent of meeting, because the cloud abode thereon, and the glory of Jehovah filled the tabernacle." — Exodus 40:35 (ASV)

Moses was not able to enter into the tent. —Apparently, Moses, seeing the cloud descend, as it had been accustomed to do upon the temporary “tent of meeting” (Exodus 33:9), attempted to re-enter the Tabernacle which he had left, but was unable; the “glory” forbade approach. (Compare the effect of the “glory” when it descended on Solomon’s Temple, 1 Kings 8:11; 2 Chronicles 5:14; 2 Chronicles 7:2.)