Deuteronomy 28:58

58.If thou wilt not observe to do all the words of this law. Inasmuch as even believers, although they are disposed to a willing obedience to the Law, and earnestly apply themselves to it, are still impeded and withheld by the infirmity of their flesh from fulfilling their duty, care and attention is here demanded of them; for “to observe ( custodire) to do” is equivalent to giving sedulous and diligent heed. Now, God declares that, unless the Israelites thoroughly devote themselves to the keeping of the Law, vengeance is prepared for their neglect. It is indeed a harsh and severe threat whereby transgression in any respect is without remission; for perfect obedience is required by the words, “to do all the words that are written in the Law.” But it is necessary that we should bear in mind what I have already shewn, that Moses was thus severe in his exactions, in order that the people, being convinced of their condemnation, should betake themselves to the mercy of God; for no one longs after Christ, unless he first abandons all confidence in his works, and rests all his hope of salvation in gratuitous pardon. The curse here recorded so awaits the transgressors of the Law, that, whilst God pardons His children, He at the same time sometimes chastises them, and executes upon the reprobate the vengeance they deserve. The fountain-head of obedience is indicated when it is said, “that thou mayest fear the Lord;” for all virtues are but smoke, which do not spring from the fear of God. Moreover, in order that their contempt may be without excuse, God’s name is called “glorious and fearful;” for it is a mark of gross stupidity, when God’s majesty and glory are openly set before us, not to be affected with becoming reverence so as to humble ourselves before Him. He, however, threatens something more terrible than before, when he says that the plagues shall be wonderful not only on the parents but on their children and descendants; instead of which some construe it, (250) He shall increase in a wonderful manner; and others, He shall separate; but this is too constrained and obscure. The word פלא, phela, signifies to be wonderful, or secret and hidden: thus, in my opinion, he means extraordinary and incredible modes of vengeance which shall surpass the comprehension of the human mind. He puts plagues and sicknesses in apposition with each other, as explaining by the latter of what nature the plagues shall be; unless, perhaps, it may be rather thought that the species is appended to the genus, which seems to be more probable. Further, he calls the plagues veritable, or faithful; either because they shall certainly occur, or because they shall continue to the end; for the Hebrew word נאמנית, (251) neumanoth, is explained in both ways; and undoubtedly it sometimes signifies veracious, or what does not deceive, sometimes firm and stable, or perpetual; and this sense appears to me to suit it best here, so that continued duration should be added to the greatness of the plagues.

He again mentions “the diseases of Egypt,” not those which they had themselves suffered in Egypt, but those under which they had seen the Egyptians laboring. He says, therefore, that the severity of God against unbelievers, of which they had been spectators, should fall upon their own heads, if they should be followers of their ungodliness; for it was natural that they should tremble at the judgments of God, whereof they had been eye-witnesses; and not only so, but at which they had trembled for fear.