Exodus 3:1-2

Young's Literal Translation

3 And Moses hath been feeding the flock of Jethro his father-in-law, priest of Midian, and he leadeth the flock behind the wilderness, and cometh in unto the mount of God, to Horeb;

² and there appeareth unto him a messenger of Jehovah in a flame of fire, out of the midst of the bush, and he seeth, and lo, the bush is burning with fire, and the bush is not consumed.