Matthew 19:4-8 King James Version (KJV)
4 And he answered and said unto them, Have ye not read, that he which made them at the beginning made them male and female,
5 And said, For this cause shall a man leave father and mother, and shall cleave to his wife: and they twain shall be one flesh?
6 Wherefore they are no more twain, but one flesh. What therefore God hath joined together, let not man put asunder.
7 They say unto him, Why did Moses then command to give a writing of divorcement, and to put her away?
8 He saith 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.