Notes on the Bible, by Albert Barnes, [1834], at sacred-texts.com
Moses proceeds to set forth more particularly and to enforce the cardinal and essential doctrines of the Decalogue, the nature and attributes of God, and the fitting mode of honoring and worshipping Him. Two objects are indicated Deu 6:2-3, the glory of God and the welfare of man, as the grand aims that he has in view.
In the land - Better: According as the Lord the God of thy fathers promised thee a land flowing with milk and honey.
These words form the beginning of what is termed the "Shema" ("Hear") in the Jewish Services, and belong to the daily morning and evening office. They may be called "the creed of the Jews."
This weighty text contains far more than a mere declaration of the unity of God as against polytheism; or of the sole authority of the revelation that He had made to Israel as against other pretended manifestations of His will and attributes. It asserts that the Lord God of Israel is absolutely God, and none other. He, and He alone, is Jehovah (Yahweh) the absolute, uncaused God; the One who had, by His election of them, made Himself known to Israel.
Since there is but One God, and that God is Israel's God, so Israel must love God unreservedly and entirely. The "heart" is mentioned as the seat of the understanding; the "soul" as the center of will and personality; the "might" as representing the outgoings and energies of all the vital powers.
The New Testament itself requires no more than this total self-surrender of man's being to his maker Mat 22:37. The Gospel differs from the Law not so much in replacing an external and carnal service of God by an inward and spiritual one, as in supplying new motives and special assistances for the attainment of that divine love which was, from the first and all along, enjoined as "the first and great commandment."
By adopting and regulating customary usages (e. g. Egyptian) Moses provides at once a check on superstition and a means of keeping the Divine Law in memory. On the "frontlets," the "phylacteries" of the New Test. Mat 23:5, see Exo 13:16. On Deu 6:9; Deu 11:20 is based the Jewish usage of the mezuzah. This word denotes properly a door-post, as it is rendered here and in Exo 12:7, Exo 12:22; Exo 21:6 etc. Among the Jews however, it is the name given to the square piece of parchment, inscribed with Deu 6:4-9; Deu 11:13-21, which is rolled up in a small cylinder of wood or metal, and affixed to the right-hand post of every door in a Jewish house. The pious Jew touches the mezuzah on each occasion of passing, or kisses his finger, and speaks Psa 121:8 in the Hebrew language.
The Israelites were at the point of quitting a normal, life for a fixed and settled abode in the midst of other nations; they were exchanging a condition of comparative poverty for great and goodly cities, houses and vineyards. There was therefore before them a double danger;
(1) a God-forgetting worldliness, and
(2) a false tolerance of the idolatries practiced by those about to become their neighbors.
The former error Moses strives to guard against in the verses before us; the latter in Deu 7:1-11.
The command "to swear by His Name" is not inconsistent with the Lord's injunction Mat 5:34, "Swear not at all." Moses refers to legal swearing, our Lord to swearing in common conversation. It is not the purpose of Moses to encourage the practice of taking oaths, but to forbid that, when taken, they should be taken in any other name than that of Israel's God. The oath involves an invocation of Deity, and so a solemn recognition of Him whose Name is made use of in it. Hence, it comes especially within the scope of the commandment Moses is enforcing.
It shall be our righteousness - i. e., God will esteem us as righteous and deal with us accordingly. From the very beginning made Moses the whole righteousness of the Law to depend entirely on a right state of the heart, in one word, upon faith.