Exodus 3:1-3

Now Moses was pasturing the flock of his father-in-law Jethro, the priest of Midian; and he led the flock to the west side of the wilderness and came to Horeb, the mountain of God.

Then the angel of the Lord appeared to him in a blazing fire from the midst of a bush; and he looked, and behold, the bush was burning with fire, yet the bush was not being consumed.

So Moses said, “I must turn aside and see this marvelous sight, why the bush is not burning up!”