Matthew 19:7-9

7“Then why did Moses say in the law that a man could give his wife a written notice of divorce and send her away?” they asked.

8Jesus replied, “Moses permitted divorce only as a concession to your hard hearts, but it was not what God had originally intended.

9And I tell you this, whoever divorces his wife and marries someone else commits adultery—unless his wife has been unfaithful.”