The 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.” So Moses set out with his assistant Joshua, and Moses went up into the mountain of God. To 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.”
Then Moses went up on the mountain, and the cloud covered the mountain. The 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. Now 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. Moses entered the cloud, and went up on the mountain. Moses was on the mountain for forty days and forty nights.
2 Peter 1:16-21
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. For 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.” We ourselves heard this voice come from heaven, while we were with him on the holy mountain.
So 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. First of all you must understand this, that no prophecy of scripture is a matter of one’s own interpretation, because no prophecy ever came by human will, but men and women moved by the Holy Spirit spoke from God.
Six days later, Jesus took with him Peter and James and his brother John and led them up a high mountain, by themselves. And he was transfigured before them, and his face shone like the sun, and his clothes became dazzling white. Suddenly there appeared to them Moses and Elijah, talking with him. Then 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.” While 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!” When the disciples heard this, they fell to the ground and were overcome by fear. But Jesus came and touched them, saying, “Get up and do not be afraid.” And when they looked up, they saw no one except Jesus himself alone.
As 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.”