Theophylact of Ohrid — as excerpted in the Catena Aurea on Mark 9:9-13

“For again, John rebuked vice, and was a zealous man, and a hermit like Elias; but they heard him not, as they will hear Elias, but killed him in wicked sport, and cut off his head; wherefore there follows, And they have done unto him whatsoever they listed, as it is written of him.”