John Calvin Commentary Matthew 19:3

"And there came unto him Pharisees, trying him, and saying, Is it lawful [for a man] to put away his wife for every cause?" — Matthew 19:3 (ASV)

And the Pharisees came to him, tempting him. Though the Pharisees lay snares for Christ and cunningly endeavor to deceive him, yet their malice proves to be highly useful to us, as the Lord knows how to turn, in a wonderful manner, to the advantage of his people all the schemes of wicked men to overthrow sound doctrine. For, through this occurrence, a question concerning the freedom of divorce was settled, and a fixed law was established concerning the sacred and indissoluble bond of marriage. The reason for this quibbling was that the reply, however it might be given, could not, as they thought, fail to be offensive.

They ask, Is it lawful for a man to divorce his wife for any cause whatever? If Christ replies in the negative, they will exclaim that he wickedly abolishes the Law; and if in the affirmative, they will proclaim that he is not a prophet of God, but rather a pander, who gives such approval to the lust of men. Such were the calculations they had made in their own minds.

But the Son of God, who knew how to take the wise in their own craftiness (Job 5:13), disappointed them, sternly opposing unlawful divorces and at the same time showing that he presents nothing inconsistent with the Law. For he addresses the whole question under two main points: first, that the order of creation ought to serve as a law, meaning that the husband should maintain conjugal fidelity throughout his entire life; and second, that divorces were permitted, not because they were lawful, but because Moses had to deal with a rebellious and unmanageable nation.