John Lightfoot on Luke 9:8

[That one of the old prophets was risen again.] So is the expression again, verse 19; in which sense that prophet must be taken, John 1:21,25, that is one of the old prophets that is risen again.

Although they looked for no other prophet (excepting Elias only) before the appearing of the Messiah, yet doth it seem that they had an opinion that some of the ancient prophets should rise again, and that the time was now at hand wherein they should so do; and that because they made such frequent mention of it in their common talk, that "some one of the old prophets had risen again."