Nebuchadnezzar was furious and ordered the furnace heated seven times hotter!

Then Nebuchadnezzar was furious with Shadrach, Meshach and Abednego, and his attitude toward them changed. He ordered the furnace heated seven times hotter than usual and commanded some of the strongest soldiers in his army to tie up Shadrach, Meshach and Abednego and throw them into the blazing furnace. Daniel 3:19-20

Nebuchadnezzar burst into an uncontrollable rage at the reply of the three Hebrews. He would not be defied and ordered that the furnace be heated seven times hotter than usual (meaning as hot as possible).

THEY WERE BOUND AND THROWN INTO THE BLAZING FURNACE

So these men, wearing their robes, trousers, turbans and other clothes, were bound and thrown into the blazing furnace. The king’s command was so urgent and the furnace so hot that the flames of the fire killed the soldiers who took up Shadrach, Meshach and Abednego, and these three men, firmly tied, fell into the blazing furnace. Daniel 3:21-23

The furnace was so hot that in fact the guards whom he detailed to bind the prisoners and throw them into the furnace, themselves perished in the flames. But that did not stop the three from falling in.

WEREN’T THREE MEN THROWN INTO THE FIRE?

Then King Nebuchadnezzar leaped to his feet in amazement and asked his advisers, “Weren’t there three men that we tied up and threw into the fire?”

They replied, “Certainly, Your Majesty.”

He said, “Look! I see four men walking around in the fire, unbound and unharmed, and the fourth looks like a son of the gods.” Daniel 3:24-25

It seems that the brick kiln was a domed structure with a place at the bottom for the removal of ashes. Apparently, he looked through the hole in the bottom and saw the young men walking about.

A Christophany is an appearance of the pre-incarnate Christ in the Old Testament, or after his ascension. A Christophany is thus a special case of a theophany. The word, “Theophany” is derived from the Ancient Greek, meaning "appearance of God." Whenever someone received a visit from “the angel of the LORD,” this was in fact the pre-incarnate Christ. The visible appearances of God in human or angelic form in the Old Testament, is actually the Son of God manifesting Himself prior to His incarnation. The fourth man in the fire was the Son of God. He most probably had a radiant appearance since the king said that the fourth man looked supernatural.

SERVANTS OF THE MOST HIGH GOD

Nebuchadnezzar then approached the opening of the blazing furnace and shouted, “Shadrach, Meshach and Abednego, servants of the Most High God, come out! Come here!” So Shadrach, Meshach and Abednego came out of the fire, Daniel 3:26

Note that the king calls the three Hebrew men by name but makes no mention of the fourth man. The king gives glory to the God that he had just mocked and calls Shadrach, Meshach and Abednego servants of the Most High God. Although Nebuchadnezzar acknowledged Yehovah to be supreme above other gods, he still did not cease to believe in these other gods.