This verse may have been the most important in the entire chapter. In the original Malachai, the part of Israel who still feared the Lord had a “book of remembrance written.” This is the image of the heavenly book in which the names of the righteous are written:
Philippians 4:3
3 And I intreat thee also, true yokefellow, help those women which laboured with me in the gospel, with Clement also, and with other my fellowlabourers, whose names are in the book of life. (italics added)
Revelation 13:4-8
4 And they worshipped the dragon which gave power unto the beast: and they worshipped the beast, saying, Who is like unto the beast? who is able to make war with him?
5 And there was given unto him a mouth speaking great things and blasphemies; and power was given unto him to continue forty and two months.
6 And he opened his mouth in blasphemy against God, to blaspheme his name, and his tabernacle, and them that dwell in heaven.
7 And it was given unto him to make war with the saints, and to overcome them: and power was given him over all kindreds, and tongues, and nations.
8 And all that dwell upon the earth shall worship him, whose names are not written in the book of life of the Lamb slain from the foundation of the world. (italics added).
For Malachi, the imagery is of this heavenly book recording the righteous. In the context of Hebrew history, this was an image that indicated that the Lord would remember the righteous even when the world did not. However, in the immediate context in which this chapter is being cited, the Bountiful context is very different.
The Lord is citing this chapter of Malachi as part of his discussion of the value of the written scriptures. In the particular context, it is the value of the Nephite written scriptures. For the Bountiful context, the command to write a book of remembrance is a direct reference to the Book of Mormon. The Lord has told them that one of the events that precedes the coming of the Triumphant Messiah will be the coming forth of their record, or the Book of Mormon. They have been told that written scriptures are essential, so much so that the Messiah himself would examine them and require that they be accurate (when he requires the correction to the record of Samuel). Thus the entire context leading up to Malachi is emphasizing the scriptural record, and it is punctuated in this verse.