Now Moses was keeping the flock of his father-in-law, Jethro, the priest of Midian, and he led his flock to the west side of the wilderness and came to Horeb, the mountain of God. And the angel of the Lord appeared to him in a flame of fire out of the midst of a bush. He looked, and behold, the bush was burning, yet it was not consumed. And Moses said, “I will turn aside to see this great sight, why the bush is not burned.” When the Lord saw that he turned aside to see, God called to him out of the bush, “Moses, Moses!” And he said, “Here I am.” Then he said, “Do not come near; take your sandals off your feet, for the place on which you are standing is holy ground.” And he said, “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 to look at God.
Exodus 3:1-6 (ESV)
Exodus 3:1-6 describes the calling of Moses in an extraordinary event. God reveals Himself as omnipotent over creation as He speaks to Moses from a burning bush which is never consumed. God calls “Moses, Moses” with the repetition of the name signifying affection. He instructs Moses to remove his sandals because the holy God (without equal / without sin) is in this place. Moses responds in fear and humility; God responds with reassurance and sends Moses out to serve him.