1 Nephi 15:13

And now, the thing which our father meaneth concerning the grafting in of the natural branches through the fulness of the Gentiles, is, that in the latter days, when our seed shall have dwindled in unbelief, yea, for the space of many years, and many generations, after that the Messiah hath manifested himself in body unto the children of men, then shall the fulness of the Gospel of the Messiah come unto the Gentiles, and from the Gentiles unto the remnant of our seed;

What our father means about grafting in the natural branches through the fullness of the Gentiles is this: In the last days, when our descendants have lost their faith for many years and many generations after the Messiah has shown himself to people, then the fullness of the Messiah’s gospel will come to the Gentiles, and from the Gentiles to the remnant of our descendants.

“Here’s what Dad meant about grafting branches back through the Gentiles: In the future, after our descendants lose their faith—long after the Messiah appears to humanity—the complete gospel will go to the Gentiles first. Then from the Gentiles, it will reach what’s left of our family line.”