In his discourse on the coming life and mission of Jesus Christ, Alma mentions the testimonies of several earlier prophets concerning this event, including this statement about Moses: ". . . he was spoken of by Moses; yea, and behold a type was raised up in the wilderness, that whosoever would look upon it might live. And many did look and live." (Alma 33:19.)
The "type" mentioned by Alma evidently refers to the brass serpent that was lifted up on a pole by Moses when he was leading the people of Israel out of Egypt. This symbol is discussed later in the Book of Mormon; see the material listed after Helaman 8:13-15.