John Chrysostom

(Hom. xx) He asks as man, Jesus answers as God: Jesus answered and said unto him, Before that Philip called thee, when thou wast under the fig tree, I saw thee: not having beheld him as man, but as God discerning him from above. I saw thee, He says, that is, the character of thy life, when thou wast under the fig tree: where the two, Philip and Nathanael, had been talking together alone, nobody seeing them; and on this account it is said, that on seeing him a long way off, He said, Behold an Israelite indeed; whence it appears that this speech was before Philip came near, so that no suspicion could attach to Christ’s testimony. Christ would not say, I am not of Nazareth, as Philip told you, but of Bethlehem; in order to avoid an argument: (ἀμφισβητήσιμον λόγον.) and because it would not have been sufficient proof, had He mentioned it, of His being the Christ. He preferred rather proving this by His having been present at their conversation.