Matthew 19:8

Because of the hardness of your hearts— He meant their passionate, stubborn, perverse temper, which was such, that had they not been permitted to divorce their wives, some would not have scrupled to murder them; others would have got rid of them by suborning witnesses to prove the crime of adultery against them. Others would have reckoned it great mildness, if they had contented themselves with separating from their wives, and living unmarried. Moses therefore acted as a prudent lawgiver in allowing other causes of divorce besides adultery; because, by admitting the less, he avoided the greater evil. At the same time the Jews, whose hardness of heart rendered this expedient necessary, were chargeable with all the evils that followed it; for which reason, as often as they divorced their wives, unless in the case of adultery, they sinned against the original law of marriage, and were criminal in the sight of God, notwithstanding that their law allowed such divorces. Our Lord, as Grotius well observes, stronglyintimates, that a more tender disposition than that whichcharacterizedthe Jews under the Mosaic dispensation, might justly be expected from his disciples.