Fiery serpents - The epithet Deuteronomy 8:15; Isaiah 14:29; Isaiah 30:6 denotes the inflammatory effect of their bite. The peninsula of Sinai, and not least, the Arabah, abounds in mottled snakes of large size, marked with fiery red spots and wavy stripes, which belong to the most poisonous species, as the formation of the teeth clearly show.
Related Commentaries of Numbers 21:6
Numbers 21:6
6 And the LORD sent fiery serpents among the people, and they bit the people; and much people of Israel died.