“I am one that bear witness of myself, and the Father that sent me beareth witness of me.”
John 8:18 — Greek Interlinear
Church Fathers on John 8:18
Our Lord having said, I am the Light of the world; and, he that follows Me, walks not in darkness, the Jews wish to overthrow what He has said: The Pharisees therefore said to Him, you bear record of Yourself, Your record is not true.
As if our Lord Himself were the only (one that bore) witness to Himself; whereas the truth was that He had, before His incarnation, sent many witnesses to prophesy of His Sacraments.
The witness of light is true, whether the light show itself, or other things. The Prophet spoke the truth, but whence had he it, but by drawing from the fount of truth? Jesus then is a competent witness to Himself: For I know whence I come, and whither I go: this has reference to the Father; for the Son gave glory to the Father who sent Him. How greatly then should man glorify the Creator, who made Him. He did not separate from His Father, however, when He came, or desert us…