1 Nephi 13: 21-29, 38-42; 2 Nephi 3: 12

 

How do the Bible and the Book of Mormon work together?

"21 And the angel said unto me: Knowest thou the meaning of the book?

22 And I said unto him: I know not.

23 And he said: Behold it proceedeth out of the mouth of a Jew. And I, Nephi, beheld it; and he said unto me: The book that thou beholdest is a record of the Jews, which contains the covenants of the Lord, which he hath made unto the house of Israel; and it also containeth many of the prophecies of the holy prophets; and it is a record like unto the engravings which are upon the plates of brass, save there are not so many; nevertheless, they contain the covenants of the Lord, which he hath made unto the house of Israel; wherefore, they are of great worth unto the Gentiles.

24 And the angel of the Lord said unto me: Thou hast beheld that the book proceeded forth from the mouth of a Jew; and when it proceeded forth from the mouth of a Jew it contained the fulness of the gospel of the Lord, of whom the twelve apostles bear record; and they bear record according to the truth which is in the Lamb of God.

25 Wherefore, these things go forth from the Jews in purity unto the Gentiles, according to the truth which is in God.

26 And after they go forth by the hand of the twelve apostles of the Lamb, from the Jews unto the Gentiles, thou seest the formation of that great and abominable church, which is most abominable above all other churches; for behold, they have taken away from the gospel of the Lamb many parts which are plain and most precious; and also many covenants of the Lord have they taken away.

27 And all this have they done that they might pervert the right ways of the Lord, that they might blind the eyes and harden the hearts of the children of men.

28 Wherefore, thou seest that after the book hath gone forth through the hands of the great and abominable church, that there are many plain and precious things taken away from the book, which is the book of the Lamb of God.

29 And after these plain and precious things were taken away it goeth forth unto all the nations of the Gentiles; and after it goeth forth unto all the nations of the Gentiles, yea, even across the many waters which thou hast seen with the Gentiles which have gone forth out of captivity, thou seest—because of the many plain and precious things which have been taken out of the book, which were plain unto the understanding of the children of men, according to the plainness which is in the Lamb of God—because of these things which are taken away out of the gospel of the Lamb, an exceedingly great many do stumble, yea, insomuch that Satan hath great power over them.

38 And it came to pass that I beheld the remnant of the seed of my brethren, and also the book of the Lamb of God, which had proceeded forth from the mouth of the Jew, that it came forth from the Gentiles unto the remnant of the seed of my brethren.

39 And after it had come forth unto them I beheld other books, which came forth by the power of the Lamb, from the Gentiles unto them, unto the convincing of the Gentiles and the remnant of the seed of my brethren, and also the Jews who were scattered upon all the face of the earth, that the records of the prophets and of the twelve apostles of the Lamb are true.

40 And the angel spake unto me, saying: These last records, which thou hast seen among the Gentiles, shall establish the truth of the first, which are of the twelve apostles of the Lamb, and shall make known the plain and precious things which have been taken away from them; and shall make known to all kindreds, tongues, and people, that the Lamb of God is the Son of the Eternal Father, and the Savior of the world; and that all men must come unto him, or they cannot be saved.

41 And they must come according to the words which shall be established by the mouth of the Lamb; and the words of the Lamb shall be made known in the records of thy seed, as well as in the records of the twelve apostles of the Lamb; wherefore they both shall be established in one; for there is one God and one Shepherd over all the earth.

42 And the time cometh that he shall manifest himself unto all nations, both unto the Jews and also unto the Gentiles; and after he has manifested himself unto the Jews and also unto the Gentiles, then he shall manifest himself unto the Gentiles and also unto the Jews, and the last shall be first, and the first shall be last." (1 Nephi 13: 21-29, 38-42)

"12 Wherefore, the fruit of thy loins shall write; and the fruit of the loins of Judah shall write; and that which shall be written by the fruit of thy loins, and also that which shall be written by the fruit of the loins of Judah, shall grow together, unto the confounding of false doctrines and laying down of contentions, and establishing peace among the fruit of thy loins, and bringing them to the knowledge of their fathers in the latter days, and also to the knowledge of my covenants, saith the Lord." (2 Nephi 3: 12)

And here's the beginning part of the commentary entitled: "The Lord restored many “plain and precious things” through Joseph Smith." : 

"In a vision, the Lord showed Nephi the coming forth of the Bible, explaining that “many plain and precious things” would be taken from it. Consider reading 1 Nephi 13:21–29, 38–42, looking for how the Lord planned to “make known the plain and precious things.” According to 2 Nephi 3:12, how do the Bible and Book of Mormon work together?"

The Lord did see how the plain and precious things would be taken from the Bible, and so He planned to "make known the plain and precious things" to all kindreds, tongues, and people. The Lord planned to have His words written, not just by the Jews (Judah's descendants, the stick of Judah) but by the people of Nephi (Joseph's descendants, the stick of Joseph). The stick of Judah would be known as The Bible, and the stick of Joseph would be known as The Book of Mormon. 

"19 Say unto them, Thus saith the Lord God; Behold, I will take the stick of Joseph, which is in the hand of Ephraim, and the tribes of Israel his fellows, and will put them with him, even with the stick of Judah, and make them one stick, and they shall be one in mine hand." (Ezekiel 37: 19)

The Bible and The Book of Mormon "shall grow together", each of them establishing the truth of each other—confounding false dotrines, laying down contentions, establishing peace and bringing Nephi's descendants to the knowledge of their fathers and to the knowledge of the Lord's covenants.