Daniel 7:19
Then I willed to speak the truth concerning the fourth beast that was different from all of them, exceedingly fearful, its teeth of iron and its hoofs of brass; eating, beating small, and treading down the remainder with its feet;
Daniel 7:7
After this I was seeing in the visions of the night, and lo, a fourth beast, fearful, and strong and powerful exceedingly; and great teeth of iron to it, eating and beating small, and treading down the remainder with its feet: and it being different from all the beasts that were before it; and ten horns to it.
Daniel 2:40-43
And the fourth kingdom shall be strong as iron, because that iron beats small, and makes thin all: and as iron breaks all these, it shall beat small and break.