Isaiah 6:5-9

Then I said, “Woe to me, for I am ruined! Because I am a man of unclean lips, And I live among a people of unclean lips; For my eyes have seen the King, the Lord of armies.”

Then one of the seraphim flew to me with a burning coal in his hand, which he had taken from the altar with tongs.

He touched my mouth with it and said, “Behold, this has touched your lips; and your guilt is taken away and atonement is made for your sin.” Isaiah’s Commission

Then I heard the voice of the Lord, saying, “Whom shall I send, and who will go for Us?” Then I said, “Here am I. Send me!”

And He said, “Go, and tell this people: ‘Keep on listening, but do not understand; And keep on looking, but do not gain knowledge.’