He answered and said, 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 {k} Son of God.

(k) For the angels were called the sons of God because of their excellency. Therefore the king called this angel whom God sent to comfort his own in these great torments, the son of God.

Wesley's Notes

3:25 No hurt - See how the God of nature can when he pleases control the powers of nature! The Son of God - Probably he had heard David speak of him. Jesus Christ, the Angel of the covenant, did sometimes appear before his incarnation. Those who suffer for Christ, have his gracious presence with them in their sufferings, even in the fiery furnace, even in the valley of the shadow of death, and therefore need fear no evil.

King James Translators' Notes

they...: Chaldee, there is no hurt in them

Jamieson-Fausset-Brown Bible Commentary

25. four-whereas but three had been cast in.

loose-whereas they had been cast in "bound." Nebuchadnezzar's question, in Da 3:24, is as if he can scarcely trust his own memory as to a fact so recent, now that he sees through an aperture in the furnace what seems to contradict it.

walking in . midst of . fire-image of the godly unhurt, and at large (Joh 8:36), "in the midst of trouble" (Ps 138:7; compare Ps 23:3, 4). They walked up and down in the fire, not leaving it, but waiting for God's time to bring them out, just as Jesus waited in the tomb as God's prisoner, till God should let Him out (Ac 2:26, 27). So Paul (2Co 12:8, 9). So Noah waited in the ark, after the flood, till God brought him forth (Ge 8:12-18).

like the Son of God-Unconsciously, like Saul, Caiaphas (Joh 11:49-52), and Pilate, he is made to utter divine truths. "Son of God" in his mouth means only an "angel" from heaven, as Da 3:28 proves. Compare Job 1:6; 38:7; Ps 34:7, 8; and the probably heathen centurion's exclamation (Mt 27:54). The Chaldeans believed in families of gods: Bel, the supreme god, accompanied by the goddess Mylitta, being the father of the gods; thus the expression he meant: one sprung from and sent by the gods. Really it was the "messenger of the covenant," who herein gave a prelude to His incarnation.

Matthew Henry's Concise Commentary

3:19-27 Let Nebuchadnezzar heat his furnace as hot as he can, a few minutes will finish the torment of those cast into it; but hell-fire tortures, and yet does not kill. Those who worshipped the beast and his image, have no rest, no pause, no moment free from pain, Re 14:10,11. Now was fulfilled in the letter that great promise, Isa 43:2, When thou walkest through the fire, thou shalt not be burned. Leaving it to that God who preserved them in the fire, to bring them out, they walked up and down in the midst, supported and encouraged by the presence of the Son of God. Those who suffer for Christ, have his presence in their sufferings, even in the fiery furnace, and in the valley of the shadow of death. Nebuchadnezzar owns them for servants of the most high God; a God able to deliver them out of his hand. It is our God only is the consuming fire, Heb 12:29. Could we but see into the eternal world, we should behold the persecuted believer safe from the malice of his foes, while they are exposed to the wrath of God, and tormented in unquenchable fires.