According to Nebuchadnezzar, whom had God sent to deliver the three men from the furnace?

Answer: His angel

Nebuchadnezzar declared, "Blessed be the God of Shadrach, Meshach, and Abednego, who has sent His angel and delivered His servants."

“Nebuchadnezzar declared, “Blessed be the God of Shadrach, Meshach, and Abednego, who has sent His angel and delivered His servants who trusted in Him. They violated the king’s command and risked their lives rather than serve or worship any god except their own God.”— Daniel 3:28 (BSB)