The disciples asked Him, “Why then do the scribes say that Elijah must come first?”
10. And his disciples asked him, saying. No sooner is the resurrection mentioned than the disciples imagine that the reign of Christ is commenced; “Ils imaginent que c’est l’entree du regne de Christ, et leur semble qu’ils y sont desia;” — “they imagine that it is the commencement of the kingdom of Christ, and think that they are already in it.” for they explain this...
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 his disciples asked him, saying,.... That is, these three, Peter, James, and John, before they came to the rest; whilst they were going down the mountain, or from it, to the place where the others were; for the rest knew nothing of the appearance of Elias, and so cannot be thought to join in a question concerning him. Why then say the Scribes, that Elias must first come?