John Chrysostom — as excerpted in the Catena Aurea on John 1:47-51

“(Hom. xix) Nathanael, in difficulty as to Christ coming out of Nazareth, shewed the care with which he had read the Scriptures: his not rejecting the tidings when brought him, shewed his strong desire for Christ’s coming. He thought that Philip might be mistaken as to the place. It follows, Jesus saw Nathanael coming to Him, and saith of him, Behold an Israelite indeed, in whom is no guile! There was no fault to be found with him, though he had spoken like one who did not believe, because he was more deeply read in the Prophets than Philip. He calls him guileless, because he had said nothing to gain favour, or gratify malice.”