Mark 10:6-9

But from the beginning of creation God made them male and female. [Gen. 1:27; 5:2.] For this reason a man shall leave [behind] his father and his mother and be joined to his wife and cleave closely to her permanently, And the two shall become one flesh, so that they are no longer two, but one flesh. [Gen. 2:24.] What therefore God has united (joined together), let not man separate or divide.