Exodus 3:3-5

So Moses said, “I must turn aside now and see this marvelous sight, why the bush is not burned up.” 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 come near here; remove your sandals from your feet, for the place on which you are standing is holy ground.”