'Rod of Iron' in the Bible

"He shall rule them with a rod of iron; as when potter's vessels are broken in pieces"

And she gave birth to a son, a male child, who is to rule all the nations with a rod of iron; and her child was caught up to God and to his throne.

From his mouth comes a sharp sword with which to strike down the nations, and he will rule them with a rod of iron; he treads the wine press of the fury of the wrath of God the Almighty.