Suddenly Moses and Elijah appeared before them, talking with Jesus.
3. And, lo, there appeared to them Moses and Elijah. It is asked, Were Moses and Elijah actually present? or was it only an apparition that was exhibited to the disciples, as the prophets frequently beheld visions of things that were absent? Though the subject admits, as we say, of arguments on both sides, yet I think it more probable that they were actually brought to that place.
We have here the story of Christ's transfiguration; he had said that the Son of man should shortly come in his kingdom, with which promise all the three evangelists industriously connect this story; as if Christ's transfiguration were intended for a specimen and an earnest of the kingdom of Christ, and of that light and love of his, which therein appears to his select and sanctified ones.
Commenting on Matthew 17:1-13
And behold there appeared unto them,.... The disciples: Moses and Elias; Moses the giver of the law, and Elias one of the chief of the prophets: one of them had been dead near a thousand and five hundred years, and the other had been caught up to heaven, about nine hundred years before this. The Jews sometimes speak of these two as together.