Matthew 19:5:

and said, ‘For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh’?

Matthew 19:6:

So then, they are no longer two but one flesh. Therefore what God has joined together, let not man separate

Matthew 19:7:

They said to Him, “Why then did Moses command to give a certificate of divorce, and to put her away?”

Matthew 19:8:

He said to them, “Moses, because of the hardness of your hearts, permitted you to divorce your wives, but from the beginning it was not so.

Matthew 19:9:

And I say to you, whoever divorces his wife, except for sexual immorality, and marries another, commits adultery; and whoever marries her who is divorced commits adultery.”