Ezekiel 3:7-9

7But the house of Israel will be unwilling to listen to you, since they are unwilling to listen to Me. For the whole house of Israel is hard-headed and hard-hearted.

8Behold, I will make your face as hard as their faces, and your forehead as hard as their foreheads. 9I will make your forehead like a diamond, harder than flint. Do not be afraid of them or dismayed at their presence, even though they are a rebellious house.”