Matthew 17:1 And after six days Jesus took with him Peter and James, and John his brother, 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 white as light. And behold, there appeared to them Moses and Elijah, talking with him. And Peter said to Jesus, “Lord, it is good that we are here. If you wish, I will make three tents here, one for you and one for Moses and one for Elijah.” He was still speaking when, behold, a bright cloud overshadowed them, and a voice from the cloud said, “This is my beloved Son, with whom I am well pleased; listen to him.” When the disciples heard this, they fell on their faces and were terrified. But Jesus came and touched them, saying, “Rise, and have no fear.” And when they lifted up their eyes, they saw no one but Jesus only. And as they were coming down the mountain, Jesus commanded them, “Tell no one the vision, until the Son of Man is raised from the dead.” And the disciples asked him, “Then why do the scribes say that first Elijah must come?” He answered, “Elijah does come, and he will restore all things. But I tell you that Elijah has already come, and they did not recognize him, but did to him whatever they pleased. So also the Son of Man will certainly suffer at their hands.” Then the disciples understood that he was speaking to them of John the Baptist.
The Transfiguration of Jesus. (Mark 9:2-13; Luke 9:28-36.) This mysterious event was intended primarily to confirm the faith of the three apostles who were to have the chief hand in founding the Church. The Lord had just announced his future sufferings and death. This prediction had been a grievous blow to Peter, and doubtless to the others also. He had stumbled at the cross, and had brought on himself a stern rebuke for his slowness and worldliness. So to comfort the chosen three under the thought of what awaited their Master, they were shown a glimpse of the glory which he has in heaven; they saw the Law and the prophets yielding subjection to him; they heard the voice of the Father announcing his Sonship. Henceforward they might take courage under all circumstances; the cross would be no infamy or disgrace – would open the way to victory and glory. Here was a foretaste of the blessedness of heaven – to be with Christ and his saints in his kingdom. Such was the Transfiguration to the three witnesses. To the world, when in due time it was made known, it taught lessons of the Incarnation, the resurrection of the body, the glory that shall be the portion of the righteous. (unknown)
Moses and Elijah: Remarkably, these two Old Testament persons appeared and spoke with the transfigured Jesus. Moses had lived some 1400 years before; Elijah some 900 years before; yet they were alive and in some sort of resurrected, glorified state. It is fair to think that these two particular persons from the Old Testament appeared because they represent the Law (Moses) and the Prophets (Elijah). The sum of Old Testament revelation came to meet with Jesus at the Mount of Transfiguration. (Guzik)
From this we see: “Saints long departed still alive; live in their personality; are known by their names; and enjoy near access to Christ.” (Spurgeon)
“If the Father says, ‘This is my Son,’ observe the graciousness of our adoption! With such a Son the Lord had no need of children. He did not make us his children because he needed sons, but because we needed a father.” (Spurgeon)
“Though the apostles saw ‘Jesus only,’ they saw quite sufficient, for Jesus is enough for time and eternity, enough to live by and enough to die by…O look to him, and though it be Jesus only, though Moses should condemn you, and Elias should alarm you, yet ‘Jesus only’ shall be enough to comfort and enough to save you.” (Spurgeon)