Isaiah 6:2-6

2Above it stood the seraphims: each one had six wings; with two he covered his face, and with two he covered his feet, and with two he flew. 3And one cried to another, and said, Holy, holy, holy, is the LORD of hosts: the whole earth is full of his glory.12 4And the posts of the door moved at the voice of him that cried, and the house was filled with smoke.3

5Then 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 my eyes have seen the King, the LORD of hosts.4 6Then one of the seraphims flew to me, having a live coal in his hand, which he had taken with the tongs from off the altar:5