וְלֹא־יָכֹ֣ל מֹשֶׁ֗ה לָבוֹא֙ אֶל־אֹ֣הֶל מוֹעֵ֔ד כִּֽי־שָׁכַ֥ן עָלָ֖יו הֶעָנָ֑ן וּכְב֣וֹד יְהוָ֔ה מָלֵ֖א אֶת־הַמִּשְׁכָּֽן׃
And Moses was not able to enter into the tent of meeting, because the cloud abode thereon, and the glory of the LORD filled the tabernacle.—
Read kabbalistic (mystical) interpretation of Exodus 40:35: and classical mystical sources.