Fact: Jesus appears many times in the Old Testament, although not always by name. For example:
In the book of Daniel, chapter 3, King Nebuchadnezzar throws Shadrach, Meshach, and Abednego into the fiery furnace for refusing to worship a pagan god. The fire does not burn them up; rather, when the king looks into the furnace he says, “Lo, I see four men loose, walking in the midst of the fire, and they have no hurt; and the form of the fourth is like the Son of God” (verse 25).
This is just one of many examples. The theological term for an appearance of Christ before he appeared in bodily form on earth is Christophany.
(Art by George Kornegay)
By the way, Isaiah 43:2 says, “When thou passest through the waters, I will be with thee; and through the rivers, they shall not overflow thee; when thou walkest through the fire, thou shalt not be burned; neither shall the flame kindle upon thee.”