Revelation 9:19 in the World English Bible
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.
Context
18 By these three was the third part of men killed, by the fire, and by the smoke, and by the brimstone, which issued out of their mouths.
19 For their power is in their mouth, and in their tails: for their tails were like unto serpents, and had heads, and with them they do hurt.
20 And the rest of the men which were not killed by these plagues yet repented not of the works of their hands, that they should not worship devils, and idols of gold, and silver, and brass, and stone, and of wood: which neither can see, nor hear, nor walk: