Ezekiel 3:9 in the King James Version
As an adamant harder than flint have I made thy forehead: fear them not, neither be dismayed at their looks, though they be a rebellious house.
Context
8 Behold, I have made your face hard against their faces, and your forehead hard against their foreheads.
9 I have made your forehead as a diamond, harder than flint. Don’t be afraid of them, neither be dismayed at their looks, though they are a rebellious house.”
10 Moreover he said to me, “Son of man, receive in your heart and hear with your ears all my words that I speak to you.