Mark 6:12 - Albert Barnes' Notes on the Bible

Preached that men should repent - See the nature of repentance explained in notes at Matthew 3:2. They were now called upon to repent and reform their lives because sin was evil, because the Messiah had come to preach forgiveness to the penitent, and because at “his” presence it was fit that the nation should turn from its sins and prepare to receive him.