At this period of time, Nabuchodonosor elated with prosperity, erected a golden statue to himself of enormous size, and ordered it to be worshipped as a sacred image. And when this was zealously gone about by all, inasmuch as their minds had been corrupted by the universal flattery which prevailed, Annanias, Azarias, and Misael kept aloof from the profane observance, being well aware that that honor was due to God alone. They were therefore, according to an edict of the king, regarded as criminals, and there was set before them, as the means of punishment, a fiery furnace, in order that, by present terror, they might be compelled to worship the statue.
But they preferred to be swallowed up by the flames rather than to commit such a sin. Accordingly, they were bound, and cast into the midst of the fire. But the flames laid hold of the agents in this execrable work, as they were forcing, with all eagerness, the victims into the fire; while— wonderful to say, and indeed incredible to all but eye-witnesses— the fire did not touch the Hebrews at all. They were seen by the spectators walking in the midst of the furnace, and singing a song of praise to God, while there was also beheld along with them a fourth person having the appearance of an angel, and whom Nabuchodonosor, on obtaining a nearer view of him, acknowledged to be the Son of God.
Then the king having no doubt that the divine power was present in the event which had taken place, sent proclamations throughout his whole kingdom making known the miracle which had taken place, and confessing that honor was to be paid to God alone. Not long after, being instructed by a vision which presented itself to him, and presently also by a voice which reached him from heaven, he is said to have done penance by laying aside his kingly power, retiring from all intercourse with mankind, and to have sustained life by herbs alone.
However, his empire was kept for him by the will of God, until the time was fulfilled, and at length duly acknowledging God, he was, after seven years, restored to his kingdom and former position. He is related, after having conquered Sedechia (whom he carried away captive to Babylon), as we have said above, to have reigned twenty-six years, although I do not find that recorded in the sacred history. But it has perhaps happened that, while I was engaged in searching out many points, I found this remark in the work of some anonymous author which had become interpolated in course of time, and in which the dates of the Babylonish kings were contained.
I did not think it right to pass the remark unnoticed, since it does in fact harmonize with the Chronicles, and thus its account agrees with us, to the effect that, through the succession of the kings, whose dates the record contained, it completed seventy years up to the first year of king Cyrus, and such in fact is the number of years which is stated in the sacred history to have elapsed from the captivity up to the time of Cyrus.
Source: Sacred History (New Advent)