Isaiah 6:4-7

And the foundations of the thresholds shook at the voice of him that cried, and the house was filled with smoke. 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, Jehovah of hosts. Then flew one of the seraphim unto me, having a live coal in his hand, which he had taken with the tongs from off the altar: and he touched my mouth with it, and said, Lo, this hath touched thy lips; and thine iniquity is taken away, and thy sin forgiven.