Exodus 3:2-5

3:2 The angel of the Lord appeared to him in a flame of fire from within a bush. He looked – and the bush was ablaze with fire, but it was not being consumed! 3:3 So Moses thought, “I will turn aside to see this amazing sight. Why does the bush not burn up?” 3:4 When the Lord saw that he had turned aside to look, God called to him from within the bush and said, “Moses, Moses!” And Moses said, “Here I am.” 3:5 God said, “Do not approach any closer! Take your sandals off your feet, for the place where you are standing is holy ground.”