Mark 10:4-8

And they said, Moses suffered to write a bill of divorcement, and to put her away.

And Jesus answered and said unto them, For the hardness of your heart he wrote you this precept.

But from the beginning of the creation God made them male and female.

For this cause shall a man leave his father and mother, and cleave to his wife;

And they twain shall be one flesh: so then they are no more twain, but one flesh.