Matt 5:31-32
³¹"It has been said, 'Anyone who divorces his wife must give her a certificate of divorce.' ³²But I tell you that anyone who divorces his wife, except for marital unfaithfulness, causes her to become an adulteress, and anyone who marries the divorced woman commits adultery.

Matt 19:3-12
³Some Pharisees came to him to test him. They asked, "Is it lawful for a man to divorce his wife for any and every reason?"
⁴"Haven't you read," he replied, "that at the beginning the Creator 'made them male and female,' ⁵and 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'? ⁶So they are no longer two, but one. Therefore what God has joined together, let man not separate."
⁷"Why then," they asked, "did Moses command that a man give his wife a certificate of divorce and send her away?"
⁸Jesus replied, "Moses permitted you to divorce your wives because your hearts were hard. But it was not this way from the beginning. ⁹I tell you that anyone who divorces his wife, except for marital unfaithfulness, and marries another woman commits adultery."
¹⁰The disciples said to him, "If this is the situation between a husband and wife, it is better not to marry."
¹¹Jesus replied, "Not everyone can accept this word, but only those to whom it has been given. ¹²For some are eunuchs because they were born that way; others were made that way by men; and others have renounced marriage because of the kingdom of heaven. The one who can accept this should accept it."

Mk 10:2-12
²Some 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.
⁴They 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. 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, ⁸and the two will become one flesh.' So they are no longer two, but one. ⁹Therefore what God has joined together, let man not separate."
¹⁰When they were in the house again, the disciples asked Jesus about this. ¹¹He answered, "Anyone who divorces his wife and marries another woman commits adultery against her. ¹²And if she divorces her husband and marries another man, she commits adultery."

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