Albert Barnes Commentary Matthew 19:4-6

"And he answered and said, Have ye not read, that he who made [them] from the beginning made them male and female, and said, For this cause shall a man leave his father and mother, and shall cleave to his wife; and the two shall become one flesh? So that they are no more two, but one flesh. What therefore God hath joined together, let not man put asunder." — Matthew 19:4-6 (ASV)

And he answered and said, etc. Instead of referring to the opinions of either party, Jesus called their attention to the original design of marriage and to the authority of Moses—an authority acknowledged by them both.

Have ye not read? (Genesis 1:27; Genesis 2:21–22).

And said, For this cause, etc. (Genesis 2:24). That is, God at the beginning made but one man and one woman; their posterity should learn that the original intention of marriage was that a man should have but one wife.

Shall leave father and mother. This means he shall bind himself more strongly to his wife than he was to his father or mother. The marriage connection is the most tender and endearing of all human relations, more tender than even that bond which unites us to a parent.

And shall cleave to his wife. The word cleave denotes a union of the firmest kind. It is, in the original, taken from gluing and means to adhere together so firmly that nothing can separate them.

They twain shall be one flesh. That is, they two, or those who were two, shall be united as one—one in law, in feeling, in interest, and in affection. They shall no longer have separate interests but shall act in all things as if they were one—animated by one soul and one wish.

The argument of Jesus here is that since they are so intimately united as to be one, and since in the beginning God made but one woman for one man, it follows that they cannot be separated except by the authority of God. Man may not put away his wife for every cause.

What God has joined together, man may not put asunder. In this decision, he really decided in favour of one of the parties; and it shows that when it was proper, Jesus answered questions, from whatever cause they might have been proposed, and however much difficulty it might involve him in.

Our Lord, in this, also showed consummate wisdom. He answered the question not from Hillel or Shammai, their teachers, but from Moses, and thus defeated their malice.