Yesha 'yahu (Isa) 6:5-8

Then I said, “Woe to me! I [too] am doomed! — because I, a man with unclean lips, living among a people with unclean lips, have seen with my own eyes the King, ADONAI-Tzva’ot!” One of the s’rafim flew to me with a glowing coal in his hand, which he had taken with tongs from the altar. He touched my mouth with it and said, “Here! This has touched your lips. Your iniquity is gone, your sin is atoned for.” Then I heard the voice of Adonai saying, “Whom should I send? Who will go for us?” I answered, “I’m here, send me!”