Matthew 5:31,matthew 5:32

1 Corinthians 7:10-11 NIV
To the married I give this command (not I, but the Lord): A wife must not separate from her husband. But if she does, she must remain unmarried or else be reconciled to her husband. And a husband must not divorce his wife.

Deuteronomy 24:1-4 NIV
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, and if after she leaves his house she becomes the wife of another man, and her second husband dislikes her and writes her a certificate of divorce, gives it to her and sends her from his house, or if he dies, then her first husband, who divorced her, is not allowed to marry her again after she has been defiled. That would be detestable in the eyes of the Lord. Do not bring sin upon the land the Lord your God is giving you as an inheritance.

Jeremiah 3:1 NIV
“If a man divorces his wife and she leaves him and marries another man, should he return to her again? Would not the land be completely defiled? But you have lived as a prostitute with many lovers — would you now return to me?” declares the Lord.

Luke 16:18 NIV
“Anyone who divorces his wife and marries another woman commits adultery, and the man who marries a divorced woman commits adultery.

Matthew 19:7 NIV
“Why then,” they asked, “did Moses command that a man give his wife a certificate of divorce and send her away?”

Matthew 19:8-9 NIV
Jesus replied, “Moses permitted you to divorce your wives because your hearts were hard. But it was not this way from the beginning. I tell you that anyone who divorces his wife, except for sexual immorality, and marries another woman commits adultery.”

Romans 7:3 NIV
So then, if she has sexual relations with another man while her husband is still alive, she is called an adulteress. But if her husband dies, she is released from that law and is not an adulteress if she marries another man.