Matthew 19:3-9

3And Pharisees came up to him and tested him by asking, “Is it lawful to divorce one’s wife for any cause?” 4He answered, “Have you not read that he who created them from the beginning made them male and female, 5and said, ‘Therefore a man shall leave his father and his mother and hold fast to his wife, and the two shall become one flesh’? 6So they are no longer two but one flesh. What therefore God has joined together, let not man separate.” 7They said to him, “Why then did Moses command one to give a certificate of divorce and to send her away?” 8He said to them, “Because of your hardness of heart Moses allowed you to divorce your wives, but from the beginning it was not so. 9And I say to you: whoever divorces his wife, except for sexual immorality, and marries another, commits adultery.”