Luke 9:29

And as he was praying, the fashion of his countenance was altered, and his raiment became white and dazzling.

This was an objective occurrence, not a mere vision, or impression of some kind on the minds of the apostles who saw it. Long, long afterward, John would write, "And we beheld his glory, glory as of the only begotten from the Father, full of grace and truth" (John 1:14).

And as he was praying ... Jesus here faced a great crisis in his life, issuing in his deliberate choice of the way of suffering for human salvation. As Geldenhuys noted, "Suffering was for Christ no unavoidable necessity, no matter of force, but of voluntary and willing obedience."[3] In view of all that occurred in this event, it seems that this heavenly experience was given to Jesus by the Father, as much for our Lord's encouragement as it was for the enlightenment of the apostles.