What did the seraph put on Isaiah's mouth in chapter 6?
They ... entered into a curse, and into an oath ... that we would not give our daughters unto the people of the land, not take their daughters for our sons. Nehemiah 10:29
Then flew one of the seraphims unto me, having a live coal in his hand, which he had taken with the tongs from off the altar:
And he laid it upon my mouth. Isaiah 6:6