זוהר שמות — דף קלא ע”א

The burden of Dumah is a hidden prophecy standing in whisper, a mystery of the supreme faith that cannot be revealed. The mystery of faith is built in degrees within degrees - shell within shell and marrow within marrow. When the Holy One blessed be He revealed Himself to Israel, He did so through nested levels: from Sinai (the most hidden), from Seir (more manifest), from Paran (another degree). The guardian of this night is Metatron, and the night receives special protection from the Holy One, as attested by the verse: a night of watching (leil shimurim).