Deuteronomy 30:9 And the LORD thy God will make thee plenteous in every work of thine hand, in the fruit of thy body, and in the fruit of thy cattle, and in the fruit of thy land, for good: for the LORD will again rejoice over thee for good, as he rejoiced over thy fathers:
10 If thou shalt hearken unto the voice of the LORD thy God, to keep his commandments and his statutes which are written in this book of the law, and if thou turn unto the LORD thy God with all thine heart, and with all thy soul.
11 For this commandment which I command thee this day, it is not hidden from thee, neither is it far off.
12 It is not in heaven, that thou shouldest say, Who shall go up for us to heaven, and bring it unto us, that we may hear it, and do it?
13 Neither is it beyond the sea, that thou shouldest say, Who shall go over the sea for us, and bring it unto us, that we may hear it, and do it?
14 But the word is very nigh unto thee, in thy mouth, and in thy heart, that thou mayest do it.

Moses told Israel that they would enjoy abundance and God's full provision in the land He would give them if they did one thing: be righteous before Him by obeying the law. At Sinai, Israel said all that Moses had said they would do (Exodus 19:8). They had told him they accepted the law of God to do it. It was not hidden to them on how to be righteous before their holy God. We know they failed at keeping it because the result of trying to keep the entire law was impossible. Man in his fallen condition could not keep it to the letter, and that was the point God tried to make to them. It was their schoolmaster to lead them to Christ when He would come. Thus, in the New Testament, Paul could tell the Church,

Romans 10:4 For Christ is the end of the law for righteousness to every one that believeth.
5 For Moses describeth the righteousness which is of the law, That the man which doeth those things shall live by them.
6 But the righteousness which is of faith speaketh on this wise, Say not in thine heart, Who shall ascend into heaven? (that is, to bring Christ down from above:)
7 Or, Who shall descend into the deep? (that is, to bring up Christ again from the dead.)
8 But what saith it? The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach;
9 That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.
10 For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.
11 For the scripture saith, Whosoever believeth on him shall not be ashamed.

In verse 10, Paul gives the good news. Where Israel tried to keep the law for righteousness, Paul states that Christ is the end of the law as a means to be righteous before God simply by believing on Him in His finished work. The very next verse says this: "But the righteousness which is of faith speaketh on this wise." It wasn't a matter of doing the things of the law, but the "doing" was now a matter of placing faith in Christ who would make believers keepers of the Law, which He would write on their hearts. Moses related to Israel the law; Paul preached the word of faith about Christ. And, there is a choice in both instances:

Deuteronomy 30:15 See, I have set before thee this day life and good, and death and evil;
16 In that I command thee this day to love the LORD thy God, to walk in his ways, and to keep his commandments and his statutes and his judgments, that thou mayest live and multiply: and the LORD thy God shall bless thee in the land whither thou goest to possess it.

In giving them the law, God laid before them "life and good, and death and evil," meaning there were blessings to be had in the land if they walked righteously according to the law, and curses if they didn't. The call of Israel seemed simple: just love the Lord God, walk in His ways, and keep his commandments, statutes and judgments. But they failed. The law didn't fail, man did, and they would not enter the land permanently and what blessings they had received would be lost. What would especially cause them to not possess the land and prolong their days there was falling into idolatry, the worship of false gods:

Deuteronomy 30:17 But if thine heart turn away, so that thou wilt not hear, but shalt be drawn away, and worship other gods, and serve them;
18 I denounce unto you this day, that ye shall surely perish, and that ye shall not prolong your days upon the land, whither thou passest over Jordan to go to possess it.
19 I call heaven and earth to record this day against you, that I have set before you life and death, blessing and cursing: therefore choose life, that both thou and thy seed may live:
20 That thou mayest love the LORD thy God, and that thou mayest obey his voice, and that thou mayest cleave unto him: for he is thy life, and the length of thy days: that thou mayest dwell in the land which the LORD sware unto thy fathers, to Abraham, to Isaac, and to Jacob, to give them.
31:1 And Moses went and spake these words unto all Israel.

Moses gave the Law to Israel, but he also gave Israel a promise:

Dueteronomy 18:13 Thou shalt be perfect with the LORD thy God.
14 For these nations, which thou shalt possess, hearkened unto observers of times, and unto diviners: but as for thee, the LORD thy God hath not suffered thee so to do.
15 The LORD thy God will raise up unto thee a Prophet from the midst of thee, of thy brethren, like unto me; unto him ye shall hearken;

In the book of Acts 3:22-23, Peter repeated this passage, as did Stephen in Acts 7:37. Jesus is the Prophet they all pointed to, Moses looking to the future, Peter and Stephen to the past. God first gave the Law, then He gave the one who, at the cost of His shed blood, would send the Holy Spirit to indwell all who believe. Moses had said, "If thou shalt hearken unto the voice of the LORD thy God, to keep his commandments and his statutes which are written in this book of the law, and if thou turn unto the LORD thy God with all thine heart," then they would enter the land permanently. Through faith in the shed blood of Christ and His resurrection, He would send the Holy Spirit to indwell them and would cause believers to "hearken unto the voice of the Lord." He would bring the love of God into the heart of the believer also:

Romans 5:5 And hope maketh not ashamed; because the love of God is shed abroad in our hearts by the Holy Ghost which is given unto us.
6 For when we were yet without strength, in due time Christ died for the ungodly.

Finally, He would work in the believer to sanctify him through the word so he could "turn unto the LORD thy God with all thine heart." Yet, even here, in Christ, the words of God to Moses and Peter and Stephen take on an ominous reality:

Acts 3:22 For Moses truly said unto the fathers, A prophet shall the Lord your God raise up unto you of your brethren, like unto me; him shall ye hear in all things whatsoever he shall say unto you.
23 And it shall come to pass, that every soul, which will not hear that prophet, shall be destroyed from among the people.

Deuteronomy 30:15 See, I have set before thee this day life and good, and death and evil;

In Christ, God has laid before the world "life and good, and death and evil." Many will fall into the idolatry of the last days, and there will be an image the whole world will pay homage to. They won't accept Christ, and God will judge them because they have rejected Christ and chosen death and evil. But, there will be those who have believed and received the Spirit. It will be these who will have "hearken[ed] unto the voice of the LORD thy God, . . . keep his commandments and his statutes which are written in this book of the law [by the Spirit], and . . . turn[ed] unto the LORD [their] God with all [their] heart, and with all [their] soul." These are they who will have listened to God's Prophet, our Lord Jesus Christ, by His Spirit through His word. Just as Moses brought to Israel the sacrifices for sin by which their sins were covered, so Christ, in His first coming, brought about eternal salvation. Moses did not enter the land, but died before Israel entered. This foreshadowed Christ, who entered heaven on our behalf to establish eternal redemption, but will come a second time, foreshadowed in Joshua, to lead all who have believed into the Millennial kingdom. Life and good, death and evil - it is clear who holds the keys to these:

Revelation 1:18 I am he that liveth, and was dead; and, behold, I am alive for evermore, Amen; and have the keys of hell and of death.

Romans 2:16 In the day when God shall judge the secrets of men by Jesus Christ according to my gospel.