[Edited by Ellopos from Wikipedia articles.]
Septuagint is a witness for three more chapters not found in the Hebrew and Aramaic text of the book of Daniel. These chapters are found in the Greek / Septuagint version of the Old Testament, the earliest Greek translation, which reflects a text that is older than the Masoretic. These additions are accepted as canonical in the Roman Catholic, the Orthodox, and Syriac Bibles. Most Protestant Bibles exclude these passages as apocrypha.
The Prayer of Azariah and Song of the Three Holy Children: Daniel 3:24–90 inserted between verses 23 and 24 (v. 24 becomes v. 91) in the Protestant canon, incorporated within the Fiery Furnace episode.
Susanna and the Elders: before Daniel 1:1, a prologue in early Greek manuscripts; chapter 13 in the Vulgate
Bel and the Dragon: after Daniel 12:13 in Greek, an epilogue; chapter 14 in the Vulgate
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This is a lengthy passage that appears after Daniel 3:23 in Roman Catholic and Orthodox Bibles, as in the ancient Greek Septuagint version. The passage is omitted from most Protestant Bibles as an apocryphal addition.
The passage includes three main components. The first is the penitential prayer of Daniel’s friend Azariah (called Abednego in Babylonian, according to Daniel 1:6–7) while the three youths were in the fiery furnace. The second component is a brief account of a radiant figure who met them in the furnace yet who was unburned. This is said to be an angel, or interpreted by Christians as a prefigurement or theophany of Jesus Christ, in the same vein as Melchisedek. The third component is the hymn of praise they sang when they realized their deliverance. The hymn includes the refrain, “Praise and exalt Him above all forever…”, repeated many times, each naming a feature of the world.