No earlier than about A.D. 64, Peter's Second Epistle (1:16-21) insists: "We have not followed cunning-devised fables! We made known to you the power and coming of our Lord Jesus Christ and were eyewitnesses of His majesty…. We heard!…. [Yet,] we have too a more sure word of prophecy…. Know this — that no forthtelling of the Scripture is from any private interpretation! For the forthtelling did not in olden times come by the will of man. But holy men of God spoke as they were moved by the Holy Ghost."
Here, Calvin comments (Epistles of St. Peter, Eerdmans’s ed., pp. 337-44): "Peter declares that he was an eyewitness, because he has seen with his own eyes the glory of Christ which he describes. He contrasts this knowledge with the kind of cunningly-devised fables which astute men are in the habit of inventing to entangle the minds of the simple…. What is meant, is a subtle invention with intent to deceive….