Why were the disciples not allowed to tell anyone about the Transfiguration?
Only Peter, James, and John witnessed our Lord’s Transfiguration—a prefigurement of his resurrected glory (Matt. 17:1-8). Afterward, Jesus forbade them to discuss this event until after he had risen from the dead (Matt. 17:9).
In his commentary on the Gospe ofl St. Matthew in A Catholic Commentary on Holy Scripture, Fr. A. Jones argues:
The glory passes and Jesus is once more the familiar friend. He enjoins silence: the vision is not to be spoken of until after the Resurrection, presumably to avoid premature and mistaken Messianic enthusiasm. Few, knowing of the Transfiguration, would learn to appreciate the necessity of the cross (p. 882).
By Tom Nash