This almost direct reference to the Transfiguration is one of the strongest assertions possible by the author to the apostolic authority of Peter. On one hand, this extends to the readers the assurance that their faith is grounded in the teaching of an eyewitness; on the other, it eliminates the need of the author to rely solely on his own arguments in disputing with false teachers.
16 For we did not follow cleverly devised myths when we made known to you the power and coming of our Lord Jesus Christ, but we had been eyewitnesses of his majesty.
New Revised Standard Version Bible: Anglicized Edition, copyright © 1989, 1995 National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved worldwide. http://nrsvbibles.org