Isaiah 6:6 - Matthew Poole's English Annotations on the Holy Bible

Then flew one of the seraphims unto me, by God's command, having a live coal; both a token and an instrument of purification, as the next verse explains it. From off the altar of burnt-offering, which stood in the court of the priests near the porch, and which had always coals of fire upon it, Leviticus 6:12,13. Hence he took it, to show that men are to expect purification and expiation of sin only by such means as God hath appointed, and particularly by Christ, whom that altar did manifestly represent, Hebrews 13:10.