Jewish Mysticism
Another interpretation- “Face to face [the Lord spoke to you]” (Deut. 5-4). R. Levi said- In many images (demuyot) He appeared to them. To one He appeared standing, to another sitting; to one He appeared as a youth, to another as an old man. How is this? When the Holy One, blessed be He, was revealed at the Red Sea to do battle for His children and to punish the Egyptians, He appeared as a youth… When the Holy One, blessed be He, was revealed on Mount Sinai to give the Torah to Israel, He appeared as an elder… And similarly Daniel said, “As I looked on, thrones were set in place, and the Ancient of Days took His seat” (Dan. 7-9). R. Hiyya bar Abba said- If the son of a whore should say to you, “There are two gods,” say to him- I am He at the Sea, I am He at Sinai.

Translated by Elliot Wolfson in Through a Speculum that Shines- Vision and Imagination in Medieval Jewish Mysticism, Princeton- Princeton University Press, 1994.