John 3:28 - Albert Barnes' Notes on the Bible

Bear me witness - You remember that at first I told you I was not the Messiah. As he had been “witness” to Jesus - as he came for no other end but to point him out to the Jews, they ought not to suppose that he was his superior. It was but reasonable to expect that Christ himself would be more successful than his forerunner. “I came, not to form a separate party, a special sect, but to prepare the way that he might be more successful, and that the people might be ready for his coming, and that he might have the success which he has actually met with. You should rejoice, therefore, at that success, and not envy it, for ‘his success’ is the best proof of the greatness of my word, and of its ‘success also.’”