Deuteronomy 7:12

12.Wherefore it shall come to pass. God appears so to act according to agreement, as to leave (His people) no hope of His favor, unless they perform their part of it; and undoubtedly this is the usual form of expression in the Law, in which the condition is inserted, that God will do good to His people if they have deserved it by their obedience. Still we must remember what we have elsewhere seen, that, after God has so covenanted with them, He Himself, in order that His promise may not be made of none effect, descends to the gratuitous promise of pardon, whereby He reconciles the unworthy to Himself. Thus the original covenant only avails to man’s condemnation. But when salvation is offered to them gratuitously, their works at the same time become pleasing to God. Inasmuch, however, as the cause of reward is unconnected with men and their works, all calculation of merit is out of the question: still it is profitable to believers that a reward should be promised them if they walk in the commandments of God; since, in His inestimable liberality, He deals with them as if they did something to deserve it.

In conclusion, Moses enumerates some of the proofs of God’s favor, such as fecundity, and an abundance of the fruits of the earth. It is questionable whether by what is added at the end respecting the diseases of Egypt, he means the boils which were generated by the scattered ashes, (Exodus 9:8,) or the lice which infested both man and beast, (Exodus 8:17,) or whether he extends them to those diseases which had prevailed long before the departure of the people. I am disposed to embrace the latter opinion; (224) for in Deuteronomy 28:27, after mentioning “the botch of Egypt,” he adds “emerods, and the scab, and the itch:” it is, therefore, probable that the Egyptians were subject to various maladies, from which Moses declares that the people should be free by special privilege, if only they obeyed God’s Law.