Luke 9:29-32.

29 And as he prayed, the fashion of his countenance was altered, and his raiment was white and glistering.
30 And, behold, there talked with him two men, which were Moses and Elias:
31 who appeared in glory, and spake of his decease which he should accomplish at Jerusalem.
32 But Peter and they that were with him were heavy with sleep: and when they were awake, they saw his glory, and the two men that stood with him.