Isaiah 6:7-9

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