A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
deu 30:1GREAT MERCIES PROMISED UNTO THE PENITENT. (Deu 30:1-10)
when all these things are come upon thee, . . . and thou shalt return . . . then the Lord thy God will turn thy captivity--The hopes of the Hebrew people are ardently directed to this promise, and they confidently expect that God, commiserating their forlorn and fallen condition, will yet rescue them from all the evils of their long dispersion. They do not consider the promise as fulfilled by their restoration from the captivity in Babylon, for Israel was not then scattered in the manner here described--"among all the nations," "unto the utmost parts of heaven" (Deu 30:4). When God recalled them from that bondage, all the Israelites were not brought back. They were not multiplied above their fathers (Deu 30:5), nor were their hearts and those of their children circumcised to love the Lord (Deu 30:6). It is not, therefore, of the Babylonish captivity that Moses was speaking in this passage; it must be of the dispersed state to which they have been doomed for eighteen hundred years. This prediction may have been partially accomplished on the return of the Israelites from Babylon; for, according to the structure and design of Scripture prophecy, it may have pointed to several similar eras in their national history; and this view is sanctioned by the prayer of Nehemiah (Neh 1:8-9). But undoubtedly it will receive its full and complete accomplishment in the conversion of the Jews to the Gospel of Christ. At the restoration from the Babylonish captivity, that people were changed in many respects for the better. They were completely weaned from idolatry; and this outward reformation was a prelude to the higher attainments they are destined to reach in the age of Messiah, "when the Lord God will circumcise their hearts and the hearts of their seed to love the Lord." The course pointed out seems clearly to be this: that the hearts of the Hebrew people shall be circumcised (Col 2:2); in other words, by the combined influences of the Word and spirit of God, their hearts will be touched and purified from all their superstition and unbelief. They will be converted to the faith of Jesus Christ as their Messiah--a spiritual deliverer, and the effect of their conversion will be that they will return and obey the voice (the Gospel, the evangelical law) of the Lord. The words may be interpreted either wholly in a spiritual sense (Joh 11:51-52), or, as many think, in a literal sense also (Rom. 11:1-36). They will be recalled from all places of the dispersion to their own land and enjoy the highest prosperity. The mercies and favors of a bountiful Providence will not then be abused as formerly (Deu 31:20; Deu 32:15). They will be received in a better spirit and employed to nobler purposes. They will be happy, "for the Lord will again rejoice over them for good, as He rejoiced over their fathers."
deu 30:11THE COMMANDMENT IS MANIFEST. (Deu 30:11-14)
For this commandment . . . is not hidden . . . neither is it far off--That law of loving and obeying God, which was the subject of Moses' discourse, was well known to the Israelites. They could not plead ignorance of its existence and requirements. It was not concealed as an impenetrable mystery in heaven, for it had been revealed; nor was it carefully withheld from the people as a dangerous discovery; for the youngest and humblest of them were instructed in those truths, which were subjects of earnest study and research among the wisest and greatest of other nations. They were not under a necessity of undertaking long journeys or distant voyages, as many ancient sages did in quest of knowledge. They enjoyed the peculiar privilege of a familiar acquaintance with it. It was with them a subject of common conversation, engraven on their memories, and frequently explained and inculcated on their hearts. The apostle Paul (Rom 10:6-8) has applied this passage to the Gospel, for the law of Christ is substantially the same as that of Moses, only exhibited more clearly in its spiritual nature and extensive application; and, accompanied with the advantages of Gospel grace, it is practicable and easy.
deu 30:15DEATH AND LIFE ARE SET BEFORE THE ISRAELITES. (Deu 30:15-20)
See, I have set before thee this day life and good, and death and evil--the alternative of a good and happy, or a disobedient and miserable life. Love of God and compliance with His will are the only ways of securing the blessings and avoiding the evils described. The choice was left to them, and in urging upon them the inducements to a wise choice, Moses warmed as he proceeded into a tone of solemn and impressive earnestness similar to that of Paul to the elders of Ephesus (Act 20:26-27).