John Chrysostom — as excerpted in the Catena Aurea on John 5:31-40

“(Hom. xl. 2) Even the witness of John was the witness of God: for what he said, God taught him. But to anticipate their asking how it appeared that God taught John, as if the Jews had objected that John’s witness might not be true, our Lord anticipates them by saying, “Ye sought him yourselves to enquire of him; that is why I use his testimony, for I need it not.” He adds, But these things I say that ye might be saved. As if He said, I being God, needed not this human kind of testimony. But, since ye attend more to him, and think him more worthy of credit than any one else, while ye do not believe me, though I work miracles; for this cause I remind you of his testimony. But had they not received John’s testimony? Before they have time to ask this, He answers it: He was a burning and a shining light, and ye were willing for a season to rejoice in his light. He says this to shew, how lightly they had held by John, and how soon they had left him, thus preventing him from leading them to Christ. He calls him a candle, because John had not his light from himself, but from the grace of the Holy Spirit.”