And he made thereunto four pillars of shittim wood, and overlaid them with gold: their hooks were of gold; and he cast for them four sockets of silver.
Jeremiah 1:18
For, behold, I have made thee this day a defenced city, and an iron pillar, and brasen walls against the whole land, against the kings of Judah, against the princes thereof, against the priests thereof, and against the people of the land.