Exodus 3:2-5 New Revised Standard Version (NRSV)

There the angel of the Lord appeared to him in a flame of fire out of a bush; he looked, and the bush was blazing, yet it was not consumed. Then Moses said, “I must turn aside and look at this great sight, and see why the bush is not burned up.” When the Lord saw that he had turned aside to see, God called to him out of the bush, “Moses, Moses!” And he said, “Here I am.” Then he said, “Come no closer! Remove the sandals from your feet, for the place on which you are standing is holy ground.”