Isaiah 6:4-7

And the foundations of the thresholds trembled at the voice of him who called out, and the temple was filling with smoke. Then I said, “Woe is me! For I am ruined, Because I am a man of [ceremonially] unclean lips, And I live among a people of unclean lips; For my eyes have seen the King, the LORD of hosts.” 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, “Listen carefully, this has touched your lips; your wickedness [your sin, your injustice, your wrongdoing] is taken away and your sin atoned for and forgiven.”