Matthew 19:5-8

and said, ‘For this reason a man will leave his father and mother and be united to his wife, and the two will become one flesh’? So they are no longer two, but one flesh. Therefore what God has joined together, let no one separate.” “Why then,” they asked, “did Moses command that a man give his wife a certificate of divorce and send her away?” Jesus replied, “Moses permitted you to divorce your wives because your hearts were hard. But it was not this way from the beginning.