Dr. Martin Luther continues his commentary on Deuteronomy with this summary of chapter 11 – and it´s good reading in this translation by Richard R. Caemmerer in Luther´s Works Volume 9, pages 117-119:
This chapter is a sort of conclusion to all previous exhortations concerning the First Commandment.
It repeats and drives home the blessings received in Egypt and the desert, and promises the land and future benefits which are to be received when they keep the Commandments of God and do not worship strange gods.
So far He has been discussing and urging this First Commandment, and therefore He is so concerned about it that He commands it to be taken to heart, to be bound as a sign on hands and eyes, and to be taught to the children, just as He did above; for it contains the whole sum and fulfillment of all the Commandments that follow. So we see that Moses omits nothing that pertains to the understanding of the First Commandment, just as he has amply discussed everything that promotes faith and everything that impedes it. In what follows he will deal with the rites and ceremonies of works of the same Commandment.
But he also mixes in some promises, namely, that if they cling to the Lord, He will drive out nations stronger than they. Likewise, every place their foot treads shall be theirs. He also says: “No one will stand against you. The Lord your God will lay the fear and the dread of you upon all the land into which you are about to go” (v. 25).
Then He puts a curse next to the promises. Yes, both at the same time, blessing and cursing, He commands to be spoken on Mts. Gerizim and Ebal. About this we shall speak below, for it all belongs to the final summary.1 He adds also the nature of the Promised Land as a sort of promise, namely, that it is not like the land of Egypt but is under the special care of the Lord, whose eyes are on it from the beginning of the year to the end.
The point is that He warns them to be dependent on God in faith and to know that through the favor of God the rain of this land is granted to the faithful and withheld from the unfaithful.
We know that Egypt is not moistened by rains but by the flooding of the Nile each summer. This miracle of God, like all the others, has been belittled because of its regularity. In this Egypt differs from other lands by a remarkable distinction. But the Land of Promise has mountains and valleys; therefore it is made fertile, not through the flooding of the river but through moistening rains from the sky. Not that other lands are not moistened and cared for in the same way or that the eyes of the Lord are not on them from the beginning of the year to the end, as they are on this one. For He Himself gives food to all flesh (Ps. 136:25), as the preceding chapter also says (Deut. 10:18): “He Himself gives food and clothing to the stranger,” and “He fills with gladness and food the hearts of the sons of men” (Acts 14:17).
But the difference is that no Gentiles have the promise of God in this matter. God indeed gives everything to all; but to this His own people He adds the Word of promise that they should not live by bread alone, as the rest of the nations do, but also by the Word.
In this land they are not to have care for the belly alone but much rather also for the spirit. They should not think that the land is given them to fatten them like pigs; rather, they are to nourish themselves with the Word of God and to receive everything through the Word of God, that is, to serve God. Not for the sake of the land itself but for the sake of the people in it is God concerned for the land, that He may rule them in it by faith, as is said elsewhere. He did not choose the nation because of the place, but the place because of the nation. For He did not choose Abraham and his seed on account of the land which He promised him, but He chose the land which He gave him because of Abraham.
This land, however, denotes the kingdom of Christ, which—previously occupied by godless demons, teachers, and workmongers—is freed from sin and error through the Word of the Gospel.
In it one lives through faith in such a way that with a sure and faithful conscience we are aware of being under the care of God and realize that the eyes of His grace are open over us always.
Then it is made fertile by the rains of heavenly doctrine. For it is moistened, not through the work or word of man, as in Egypt irrigation waters are conducted from one place to another, but solely through the speech of God from heaven.
The seasonal and the later rains are also discussed elsewhere. The seasonal rain is the first rain; the late rain comes afterwards. That is how a joyful harvest and abundance of produce come about, when fair weather and the warm sun follow the rain; then, when it is very hot, rain again follows. For constant rain destroys everything, just as constant summer heat and warmth do. So also not only doctrine is to circulate among the people, but after doctrine the work of faith must be practiced.
But where strength has slackened through labor and suffering, then the heart must be lifted up again, comforted, and consoled through doctrine. Thus man will grow in the knowledge of God.
On the other hand, only to teach and not to do is just as if it were always raining, and everything choked and perished. Again, to labor and suffer and not to teach is just as if summer heat were to burn constantly and the waning strength of the spirit were being quenched. Therefore both rains are necessary, the early and the late, that is, teaching and exhorting. In Rom. 12:7–8 we read: “He who teaches, in doctrine; he who exhorts, in exhorting.”