John 3:11 - Joseph Benson’s Commentary on the Old and New Testaments

We speak that we do know I, and all that truly believe in me. Or, he may refer to the testimony that was given to the truth of his doctrine by John the Baptist, and to the preaching also of his own disciples, who all concurred in testifying the same things, the certainty of which they were assured of by the illuminating influences of the Holy Spirit, and by their own experience, while it was known to Christ by his omniscience, and by the intimate acquaintance that he had with all the counsels of his Father. And testify that we have seen Here our Lord alludes to what was required in the law to qualify a man to be a witness, namely, that he should be able to declare concerning what he testified, that he had seen, or known it, Leviticus 5:1. And as Christ, therefore, had a clear perception and certain knowledge of the truth of what he said, there was the highest reason to receive his testimony, and to regard him as a true and faithful witness. And ye Jewish rulers, teachers, and people, are generally of such a disposition that ye receive not our witness Either as true or important; but disbelieve and reject, or neglect it.