2 Nephi 25:21

Wherefore, for this cause hath the Lord God promised unto me that these things which I write, shall be kept and preserved, and handed down unto my seed, from generation to generation, that the promise may be fulfilled unto Joseph, that his seed should never perish as long as the earth should stand.

Because of this, the Lord God has promised me that these things I write will be kept safe. They will be passed down to my children. They will go from one generation to the next. This is so God’s promise to Joseph will come true. His children will never die out as long as the earth stands.

That’s why the Lord God promised me these things I’m writing will be preserved and passed down through my family line, generation after generation. This fulfills the promise to Joseph—that his descendants would never disappear as long as the earth stands.