14 Those Jews, then, spoke what they saw with their father. And what was that but falsehood? But the Lord saw with His Father what He should speak; and what was that, but Himself? What, but the Word of the Father? What, but the truth of the Father, eternal itself, and co-eternal with the Father? He, then, “was a murderer from the beginning, and abode not in the truth, because there is no truth in him; when he speaks a lie, he speaks of his own, for he is a liar,”— and not only a liar, but also “the father of it;” that is, of the very lie that he speaks he is the father, for he himself begot his lie. “And because I tell you the truth, you believe me not. Which of you convicts me of sin,” as I convict both you and your father? “If I say the truth, why do ye not believe me,” but just because you are the children of the devil?
Source: Tractates on the Gospel of John (New Advent)