John Calvin on John 15:25

25. But that the word may be fulfilled. What is contrary to nature appears to be incredible. But nothing is more contrary to reason than to hate God; and, therefore, Christ says that so great was the malice with which their minds were envenomed, that they hated him without a cause Christ quotes a passage from Psalm 35:19, which, he says, is now fulfilled Not that the same thing did not happen, formerly, to David, but to reprove the obstinate malice of the nation, which reigned perpetually from age to age, being continued from grandfathers to grandchildren in unbroken succession; as if he had said, that they were in no respect better than their fathers, who hated David without a cause.

Which is written in their Law. By the word Law, he means the Psalms; for the whole doctrine of the Prophets was nothing else than an appendage to the Law; and we know that the ministry of Moses lasted till the time of Christ. He calls it their Law, not as an expression of respect for them, but to wound them more deeply by a designation which was well known among them; as if he had said, “They have a Law transmitted to them by hereditary right, in which they see their morals painted to the life.”