Exodus 3:1-2

Now Moses was keeping the flock of Jethro (Reuel) his father-in-law, the priest of Midian; and he led his flock to the west side of the wilderness and came to Horeb (Sinai), the mountain of God. The Angel of the LORD appeared to him in a blazing flame of fire from the midst of a bush; and he looked, and behold, the bush was on fire, yet it was not consumed.