Exodus 3:2-5

2And the Angel of the Lord appeared to him in a flame of fire from the midst of a bush. So he looked, and behold, the bush was burning with fire, but the bush was not consumed.

3Then Moses said, “I will now turn aside and see this great sight, why the bush does not burn.”

4So when the Lord saw that he turned aside to look, God called to him from the midst of the bush and said, “Moses, Moses!” And he said, “Here I am.”

5Then He said, “Do not draw near this place. Take your sandals off your feet, for the place where you stand is holy ground.”