Revelation 9:17
And thus I saw the horses in the vision, and them that sat on them, having breastplates of fire, and of jacinth, and brimstone: and the heads of the horses were as the heads of lions; and out of their mouths issued fire and smoke and brimstone.
Cross-references
Revelation 9:18 states the three plagues from the horses' mouths kill a third of mankind — the direct effect of what is described here.
Revelation 14:10 torments beast worshipers with fire and sulfur, echoing the same judgment elements coming from these horses' mouths.
Revelation 19:20 throws the beast and false prophet into the lake of fire with sulfur, matching the fire and sulfur from the horses here.
Both passages depict divine judgment through fire—here from the horses' mouths, in Revelation 16:8 from the sun—sharing a common plague motif.
Revelation 21:8 assigns the lake of fire with sulfur to the wicked, paralleling the fire/sulfur judgment imagery from these horses.
Genesis 19:24 recounts God raining fire and sulfur on Sodom — an OT type of divine judgment prefiguring the same elements here.
Psalm 11:6 also uses fire and brimstone as divine judgment, echoing the same imagery of fire and sulfur from the horses' mouths.
Isaiah 30:33 describes a burning place kindled by the Lord's breath like sulfur, paralleling the judgment of fire and brimstone.