Exodus 3:3-5

Then Moses said, “I will now turn aside and see this great sight, why the bush does not burn.” So 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.” Then He said, “Do not draw near this place. Take your sandals off your feet, for the place where you stand is holy ground.”