“If I bear witness of myself, my witness is not true.”—John 5:31.
“Though I bear record of myself, yet my record is true.”—John 8:14.
Our Lord, in one of these passages, expresses what was to be admitted as truth in the account of men; in the other, what his testimony was in itself. Admitting their laws or rules of evidence, his testimony would not have been credible; and therefore, in the verses following, he appeals to that of John the Baptist, and the works which he had wrought in his Father’s name, which amounted to a testimony from the Father. But though he in a manner gave up his own testimony, yielding himself to be tried even by their forms of evidence, yet would he not so far concede as to dishonour his character. He was in fact, whatever they might judge of him, the Amen, the faithful and the true witness; and, as such, he taught many things, prefacing what he delivered with that peculiar and expressive phrase—“Verily, verily, I say unto you!”
Fuller, A. G. (1988). The Complete Works of Andrew Fuller: Memoirs, Sermons, Etc. (J. Belcher, Ed.) (Vol. 1, pp. 667–684). Harrisonburg, VA: Sprinkle Publications.