Jewish Mysticism
The name [YHWH] appears in its letters to the angels and prophets in several forms and radiance and it appears in the image of the appearance of an anthropos, as it says, “Above the expanse over their heads was the semblance of a throne, in appearance like sapphire, and on top, upon this semblance of a throne, there was the semblance of a human form” (Ezek. 1-26)… it appears in “the semblance of a human form,” this refers to the Shekhinah and the angel of the glory (mal’akh ha-kavod) which is the Tetragrammaton.

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