Exodus 3:2-5

²And the angel of the LORD appeared to him in a flame of fire out of the midst of a bush; and he looked, and lo, the bush was burning, yet it was not consumed. ³And Moses said, "I will turn aside and see this great sight, why the bush is not burnt." ⁴When the LORD saw that he turned aside to see, God called to him out of the bush, "Moses, Moses!" And he said, "Here am I." ⁵Then he said, "Do not come near; put off your shoes from your feet, for the place on which you are standing is holy ground."