John 10:40-42

"The chapter ends with a note of place which is evidently and certainly historical. No forger would ever have thought of the periphrasis -where John at first baptized" … -John did no miracle: but all things that John spake of this man were true." It would be impossible to find a stronger incidental proof that the author of the Gospel had been originally a disciple of the Baptist, or at least his contemporary, and also that he is writing of things that he had heard and seen. A Gnostic, writing in Asia Minor, even though he had come into relation with disciples of John, would not have introduced the Baptist in this way. In circles that had been affected by the Baptist's teaching, and were hesitating whether they should attach themselves to Jesus, this is precisely the sort of comment that would be heard." S. p. 179.