Exodus 3
1 Ref Now Moses was looking after the flock of Jethro, his father-in-law, the priest of Midian: and he took the flock to the back of the waste land and came to Horeb, the mountain of God.
2 Ref And the angel of the Lord was seen by him in a flame of fire coming out of a thorn-tree: and he saw that the tree was on fire, but it was not burned up.