Mark 10:5-9

And Jesus answered and said to them, “Because of 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 reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh’; so then they are no longer two, but one flesh. Therefore what God has joined together, let not man separate.”