John Gill's Exposition of the Whole Bible
Matthew 17:10
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? That is, come before the Messiah comes; for certain it is, that this was the sense of the Scribes, as it was of the ancient Jews, and is still the opinion of the modern ones. They say h,
"that in the second year of Ahaziah, Elias was hid; nor will he appear, till the Messiah comes; then he will appear, and will be hid a second time; and then will not appear, till Gog and Magog come.''
And they expressly affirm i, that
"before the coming of the son of David, יבא אליהו לבשר, "Elias will come to bring the good news" of it.''
And this, they say k, will be one day before the coming of the Messiah. And Maimonides l observes,
"that there are of their wise men that say, המשיח יבא אליהו
שקודם ביאת, "that before the coming of the Messiah, Elias shall come".''
So Trypho the Jew, the same with R. Tarphon, so often mentioned in Talmudic writings, disputing with Justin Martyr, tells him m, that the Messiah,
"shall not know himself, nor have any power, μεχρι αν ελθων
Ηλιας, "till Elias comes", and anoints him, and makes him known to all.''
And hence the Targumist n often speaks of Messiah and Elias as together, and of things done by them; and in their prayers, petitions are put for them, as to come together o: this is founded upon a mistaken sense of Malachi 4:5 and which is the general sense of their commentators p. Now the Scribes made use of this popular sense, to disprove Jesus being the Messiah: they argued, that if he was the Messiah, Elias would be come; but whereas he was not come, therefore he could not be the Messiah. The disciples having just now seen Elias, are put in mind of this tenet of the Scribes, and of their use of it; and inquire of Christ, not so much about the truth of it, and the reason of their imbibing it, as why they were suffered to make use of it, to his disadvantage; and especially why they, the disciples, should be forbid publishing what they had seen; whereas, were they allowed to divulge this vision, and bear their testimony to this truth, that Elias had appeared, and they had seen him, it might be a means of stopping the mouths of these Scribes; and of convicting men of the truth of the Messiahship of Jesus, upon their own principles, and of confirming them that believed it: or else the sense is, whereas they had seen Elias, and he was gone again, without making any public appearance in the nation, their question is, how came the Scribes to say, that he should come first? and if there was any truth in this, how came it to pass, that he did not come sooner, even before Christ came in the flesh; and inasmuch as he did now appear, why he did not appear more publicly, as the person that was to come, at least, before the setting up of the kingdom and glory of the Messiah; which they might hope were at hand, and that Elias was come to usher it in: but that he did not appear publicly, and they were not allowed to speak of it, they wanted to know Christ's sense of these things; and took this opportunity as they came from the mountain, to converse with him about it.
h Seder Olam Rabba, p. 45, 46. i Gloss. in T. Bab. Erubin, fol. 43. 2. k R. Abraham ben David in Misn. Ediot, c. 8. sect. 7. l Hilch. Melacim, c. 12. sect. 2. m Dialog. cum Tryph. p. 226. n In Exod. xl. 10. Deut. xxx. 4. Lam. iv. 22. o Seder Tephillot, fol. 56. 2. 128. 2. p Aben Ezra, Kimchi, Abarbinel in loc.