Exodus 3:1-3

1Now Moses kept the flock of Jethro his father in law, the priest of Midian: and he led the flock to the backside of the desert, and came to the mountain of God, even to Horeb.

2And the angel of Yhwh appeared unto him in a flame of fire out of the midst of a bush: and he looked, and, behold, the bush burned with fire, and the bush was not consumed.

3And Moses said, I will now turn aside, and see this great sight, why the bush is not burnt.