If integrated into the book of Daniel: 3.51

Then the three, as with one mouth: As with one mouth means they were singing “together” (Good News Translation) or “with one voice” (New Revised Standard Version, New American Bible). New Jerusalem Bible has them singing “in unison,” that is, singing the same melody. This is rather technical and is not necessarily implied.

Praised and glorified and blessed God: The Greek does not specifically say they were singing, but since what follows is a hymn, singing is surely intended. Good News Translation “singing … in praise of God” pretty well encompasses the meaning of the three Greek verbs. However, the expression “in praise of God” will be awkward in some languages. “Praised God … singing” is a possible alternative.

Notice that Good News Translation moves the phrase “in the furnace” to the beginning of the sentence to avoid having the words “God” and “in the furnace” come together. It also adds the word “again” in the phrase “again started singing,” but this word should not be included.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on The Shorter Books of the Deuterocanon. (UBS Helps for Translators). New York: UBS, 2006. For this and other handbooks for translators see here.