Matthew 5 v 31-32
“It was also said, whoever divorces his wife must give her a written notice of divorce. But I say unto you, That whosoever shall put away his wife, saving for the cause of fornication, causes her to commit adultery: and whosoever shall marry her that is divorced commits adultery.
Matthew 19 v 3-8
The Pharisees also came unto Jesus, tempting Him, and saying unto Him, Is it lawful for a man to put away his wife for every cause? And He answered and said unto them, Have you not read, that He which made them at the beginning made them male and female, And He said, For this cause shall a man leave father and mother, and shall cleave to his wife: and they two shall be one flesh? Wherefore they are no more twain, but one flesh. What therefore God hath joined together, let not man put asunder. They say unto Him, Why did Moses then command to give a writing of divorcement, and to put her away? Jesus said unto them, Moses because of the hardness of your hearts suffered you to put away your wives: but from the beginning, it was not so.