And I said: "Woe is me! I am lost, for I am a man of unclean lips, and I live among a people of unclean lips; yet my eyes have seen the King, the Lord of hosts!"
Then one of the seraphs flew to me, holding a live coal that had been taken from the altar with a pair of tongs.
The seraph touched my mouth with it and said: "Now that this has touched your lips, your guilt has departed and your sin is blotted out."
References for Isaiah 6:7
Then I heard the voice of the Lord saying, "Whom shall I send, and who will go for us?" And I said, "Here am I; send me!"
And he said, "Go and say to this people: "Keep listening, but do not comprehend; keep looking, but do not understand.'
Make the mind of this people dull, and stop their ears, and shut their eyes, so that they may not look with their eyes, and listen with their ears, and comprehend with their minds, and turn and be healed."
Then I said, "How long, O Lord?" And he said: "Until cities lie waste without inhabitant, and houses without people, and the land is utterly desolate;
until the Lord sends everyone far away, and vast is the emptiness in the midst of the land.
Even if a tenth part remain in it, it will be burned again, like a terebinth or an oak whose stump remains standing when it is felled." The holy seed is its stump.
References for Isaiah 6:13