And the angel of the LORD appeared unto him in a flame of fire out of the midst of a bush: and he looked, and, behold, the bush burned with fire, but the bush was not consumed.
So when the LORD saw that he turned aside to look, He called to him from the midst of the bush and said, “Moses, Moses!”
And Moses said, “Here I am.”
Then He said, “Do not draw near this place. Take your sandals off your feet, for the place where you stand is holy ground.
I am the God of your father—the God of Abraham, the God of Isaac, and the God of Jacob.”
And Moses hid his face, for he was afraid
Exodus 3:2-5