Matthew 19:6
So they are no longer two but one flesh. What therefore God has joined together, let not man separate. The principle derived from the Genesis citations: the one-flesh union is God's joining, and no human authority (including Moses) has the right to separate what God has joined. The what God has joined together is the key: marriage is not merely a human institution but a divine act, and the divine act cannot be undone by human legal procedure.