5:30-38 Our Lord returns to his declaration of the entire agreement between the Father and the Son, and declared himself the Son of God. He had higher testimony than that of John; his works bore witness to all he had said. But the Divine word had no abiding-place in their hearts, as they refused to believe in Him whom the Father had sent, according to his ancient promises. The voice of God, accompanied by the power of the Holy Ghost, thus made effectual to the conversion of sinners, still proclaims that this is the beloved Son, in whom the Father is well pleased. But when the hearts of men are full of pride, ambition, and the love of the world, there is no room for the word of God to abide in them.

37. the Father himself … hath borne witness of me—not referring, probably, to the voice of His baptism, but (as seems from what follows) to the testimony of the Old Testament Scripture [Calvin, Lucke, Meyer, Luthardt, &c.].

neither heard his voice, &c.—never recognized Him in this character. The words are "designedly mysterious, like many others which our Lord uttered" [Stier].