Shadrach, Meshach, and Abednego (Hebrew names Hananiah, Mishael, and Azariah) are figures from chapter 3 of the biblical Book of Daniel.

[3] It forms a pair with the story of Daniel in the lions' den, both making the point that the God of the Jews will deliver those who are faithful to him.

Nebuchadnezzar commanded that they be thrown into the fiery furnace, heated seven times hotter than normal, but when the king looked, he saw four figures walking unharmed in the flames, the fourth "like a son of God," meaning he is a divine being.

[4] The legendary nature of the story is revealed by the liberal use of hyperbole – the size of the statue, the use of every kind of music, the destruction of the executioners, and the king's rage followed by his confession of the superiority of the God of Israel.

[10] When Nebuchadnezzar confronts the defiant Jewish youths who refuse to submit to his will he asks them what god will deliver them from his hands.

[11] When the three are thrown into the furnace the king sees four men walking in the flames, the fourth like "a son of gods,"[12] a divine being.

The Hebrew names of the three youths were Hananiah (חֲנַנְיָה‎ Ḥănanyā), "Yah is gracious", Mishael (מִישָׁאֵל‎ Mīšā’ēl), "Who is what El is?"

[17] The song is alluded to in odes seven and eight of the canon, a hymn sung in the matins service and on other occasions in the Eastern Orthodox Church.

The reading of the story of the fiery furnace, including the song, is prescribed for the vesperal Divine Liturgy celebrated by the Orthodox on Holy Saturday.