Eusebius of Caesarea
Catena Aurea · Lukasevangelium 9
And it came to pass about an eight days after these sayings, he took Peter and John and James, and went up into a mountain to pray. And as he prayed, the fashion of his countenance was altered, and his raiment was white and glistering. And, behold, there talked with him two men, which were Moses and Elias: Who appeared in glory, and spake of his decease which he should accomplish at Jerusalem.
Our Lord, when He made known to His disciples the great mystery of His second coming, that it might not seem that they were to believe in His words only, proceeds to works, manifesting to them, through the eyes of their faith, the image of His kingdom; as it follows, And it came to pass about an eight days after these sayings, he took Peter and John and James, and went up into a mountain to pray.