Mark 10:1-5 (NIV)
1 Jesus then left that place and went into the region of Judea and across the Jordan. Again crowds of people came to him, and as was his custom, he taught them.
2 Some Pharisees came and tested him by asking, “Is it lawful for a man to divorce his wife?”
3 “What did Moses command you?” he replied.
4 They said, “Moses permitted a man to write a certificate of divorce and send her away.”
5 “It was because your hearts were hard that Moses wrote you this law,” Jesus replied.
Deuteronomy 24:1 (NIV)
1 If a man marries a woman who becomes displeasing to him because he finds something indecent about her, and he writes her a certificate of divorce, gives it to her and sends her from his house,
Mark 10:6-9 (NIV)
6 “But at the beginning of creation God ‘made them male and female.’ 7 ‘For this reason a man will leave his father and mother and be united to his wife, 8 and the two will become one flesh.’ So they are no longer two, but one flesh. 9 Therefore what God has joined together, let no one separate.”
Mark 10:10-12 (NIV)
10 When they were in the house again, the disciples asked Jesus about this. 11 He answered, “Anyone who divorces his wife and marries another woman commits adultery against her. 12 And if she divorces her husband and marries another man, she commits adultery.”
Matthew 19:9 (NIV)
9 I tell you that anyone who divorces his wife, except for sexual immorality, and marries another woman commits adultery.”
Matthew 5:32 (NIV)
32 But I tell you that anyone who divorces his wife, except for sexual immorality, makes her the victim of adultery, and anyone who marries a divorced woman commits adultery.
1 Corinthians 7:12-16 (NIV)
12 To the rest I say this (I, not the Lord): If any brother has a wife who is not a believer and she is willing to live with him, he must not divorce her. 13 And if a woman has a husband who is not a believer and he is willing to live with her, she must not divorce him. 14 For the unbelieving husband has been sanctified through his wife, and the unbelieving wife has been sanctified through her believing husband. Otherwise your children would be unclean, but as it is, they are holy.
15 But if the unbeliever leaves, let it be so. The brother or the sister is not bound in such circumstances; God has called us to live in peace. 16 How do you know, wife, whether you will save your husband? Or, how do you know, husband, whether you will save your wife?