Albert Barnes Commentary Job 41:21

"His breath kindleth coals, And a flame goeth forth from his mouth." — Job 41:21 (ASV)

His breath kindles coals - It seems to be a flame, and to set on fire all around it. So Hesiod, in his Theogony (1.319), describing the creation of the Chimera, speaks of it as πνέουσαν ἀμαισάκετον πῦρ (pneousan amaimaketon pur), meaning “Breathing unquenchable fire.”

So Virgil, in his Georgics (2.140), writes: Haec loca non tauri spirantes naribus ignem Invertere. This is translated by Warton as: “Bulls breathing fire these furrows never have known.”

A similar phrase is found in a sublime description of the anger of the Almighty in Psalms 18:8:

There went up a smoke out of his nostrils,
And fire out of his mouth devoured:
Coals were kindled by it.