First Reading: Exodus 24:12–18
12The LORD said to Moses, "Come up to me on the mountain, and wait there; and I will give you the tablets of stone, with the law and the commandment, which I have written for their instruction." 13So Moses set out with his assistant Joshua, and Moses went up into the mountain of God. 14To the elders he had said, "Wait here for us, until we come to you again; for Aaron and Hur are with you; whoever has a dispute may go to them."
15Then Moses went up on the mountain, and the cloud covered the mountain. 16The glory of the LORD settled on Mount Sinai, and the cloud covered it for six days; on the seventh day he called to Moses out of the cloud. 17Now the appearance of the glory of the LORD was like a devouring fire on the top of the mountain in the sight of the people of Israel. 18Moses entered the cloud, and went up on the mountain. Moses was on the mountain for forty days and forty nights.
Second Reading: 2 Peter 1:16–21
16For 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. 17For he received honor and glory from God the Father when that voice was conveyed to him by the Majestic Glory, saying, "This is my Son, my Beloved, with whom I am well pleased." 18We ourselves heard this voice come from heaven, while we were with him on the holy mountain.
19So we have the prophetic message more fully confirmed. You will do well to be attentive to this as to a lamp shining in a dark place, until the day dawns and the morning star rises in your hearts. 20First of all you must understand this, that no prophecy of scripture is a matter of one's own interpretation, 21because no prophecy ever came by human will, but men and women moved by the Holy Spirit spoke from God.
Gospel: Matthew 17:1–9
Six days later, Jesus took with him Peter and James and his brother John and led them up a high mountain, by themselves. 2And he was transfigured before them, and his face shone like the sun, and his clothes became dazzling white. 3Suddenly there appeared to them Moses and Elijah, talking with him. 4Then Peter said to Jesus, "Lord, it is good for us to be here; if you wish, I will make three dwellings here, one for you, one for Moses, and one for Elijah." 5While he was still speaking, suddenly a bright cloud overshadowed them, and from the cloud a voice said, "This is my Son, the Beloved; with him I am well pleased; listen to him!" 6When the disciples heard this, they fell to the ground and were overcome by fear. 7But Jesus came and touched them, saying, "Get up and do not be afraid." 8And when they looked up, they saw no one except Jesus himself alone.
9As they were coming down the mountain, Jesus ordered them, "Tell no one about the vision until after the Son of Man has been raised from the dead."