One day Moses was tending the flock of his father-in-law, Jethro, the priest of Midian, and he went deep into the wilderness near Sinai, the mountain of God.
References for Exodus 3:1
Suddenly, the angel of the LORD appeared to him as a blazing fire in a bush. Moses was amazed because the bush was engulfed in flames, but it didn't burn up.
"Amazing!" Moses said to himself. "Why isn't that bush burning up? I must go over to see this."
When the LORD saw that he had caught Moses' attention, God called to him from the bush, "Moses! Moses!" "Here I am!" Moses replied.
"Do not come any closer," God told him. "Take off your sandals, for you are standing on holy ground."
Then he said, "I am the God of your ancestors -- the God of Abraham, the God of Isaac, and the God of Jacob." When Moses heard this, he hid his face in his hands because he was afraid to look at God.