Albert Barnes Commentary Mark 6:12

"And they went out, and preached that [men] should repent." — Mark 6:12 (ASV)

Preached that men should repent. See the nature of repentance explained in 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 fitting that the nation should turn from its sins, and prepare to receive him.