5:17-20 Let none suppose that Christ allows his people to trifle with any commands of God's holy law. No sinner partakes of Christ's justifying righteousness, till he repents of his evil deeds. The mercy revealed in the gospel leads the believer to still deeper self-abhorrence. The law is the Christian's rule of duty, and he delights therein. If a man, pretending to be Christ's disciple, encourages himself in any allowed disobedience to the holy law of God, or teaches others to do the same, whatever his station or reputation among men may be, he can be no true disciple. Christ's righteousness, imputed to us by faith alone, is needed by every one that enters the kingdom of grace or of glory; but the new creation of the heart to holiness, produces a thorough change in a man's temper and conduct.

19. Whosoever therefore shall break—rather, "dissolve," "annul," or "make invalid."

one of these least commandments—an expression equivalent to "one of the least of these commandments."

and shall teach men so—referring to the Pharisees and their teaching, as is plain from Mt 5:20, but of course embracing all similar schools and teaching in the Christian Church.

he shall be called the least in the kingdom of heaven—As the thing spoken of is not the practical breaking, or disobeying, of the law, but annulling or enervating its obligation by a vicious system of interpretation, and teaching others to do the same; so the thing threatened is not exclusion from heaven, and still less the lowest place in it, but a degraded and contemptuous position in the present stage of the kingdom of God. In other words, they shall be reduced by the retributive providence that overtakes them, to the same condition of dishonor to which, by their system and their teaching, they have brought down those eternal principles of God's law.

but whosoever shall do and teach them—whose principles and teaching go to exalt the authority and honor of God's law, in its lowest as well as highest requirements.

the same shall be called great in the kingdom of heaven—shall, by that providence which watches over the honor of God's moral administration, be raised to the same position of authority and honor to which they exalt the law.