Revelation 9:16

The sixth angel sounded. I heard a voice from the horns of the golden altar which is before God,

saying to the sixth angel who had the trumpet, “Free the four angels who are bound at the great river Euphrates!”

The four angels were freed who had been prepared for that hour and day and month and year, so that they might kill one third of mankind.

Thus I saw the horses in the vision and those who sat on them, having breastplates of fiery red, hyacinth blue, and sulfur yellow; and the horses’ heads resembled lions’ heads. Out of their mouths proceed fire, smoke, and sulfur.

By these three plagues, one third of mankind was killed: by the fire, the smoke, and the sulfur, which proceeded out of their mouths.

For the power of the horses is in their mouths and in their tails. For their tails are like serpents, and have heads; and with them they harm.