Isaiah 6:7

4 And the posts of the door moved at the voice of him that cried, and the house was filled with smoke.

5 Then said I, Woe is me! for I am undone; because I am a man of unclean lips, and I dwell in the midst of a people of unclean lips: for mine eyes have seen the King, the LORD of hosts.

6 Then flew one of the seraphims unto me, having a live coal in his hand, which he had taken with the tongs from off the altar:

7 And he laid it upon my mouth, and said, Lo, this hath touched thy lips; and thine iniquity is taken away, and thy sin purged.

8 Also I heard the voice of the Lord, saying, Whom shall I send, and who will go for us? Then said I, Here am I; send me.

9 And he said, Go, and tell this people, Hear ye indeed, but understand not; and see ye indeed, but perceive not.

10 Make the heart of this people fat, and make their ears heavy, and shut their eyes; lest they see with their eyes, and hear with their ears, and understand with their heart, and convert, and be healed.