Mark 10:6

He answered, “What did Moses command you?”

They said, “Moses allowed a certificate of divorce to be written, and to divorce her.”

But Jesus said to them, “For your hardness of heart, he wrote you this commandment.

For this cause a man will leave his father and mother, and will join to his wife,

and the two will become one flesh, so that they are no longer two, but one flesh.

What therefore God has joined together, let no man separate.”