Mosiah 14 and 15

Mosiah 14:10 reads:

"Yet it pleased the Lord to bruise him; he hath put him to grief; when thou shalt make his soul an offering for sin he shall see his seed, he shall prolong his days, and the pleasure of the Lord shall prosper in his hand."

This is talking about Jesus Christ and his Atonement.  Abinadi is quoting Isaiah.  In chapter 15, Abinadi explains this to the wicked priests of King Noah.  In Mosiah 15:10 he asks:

"...And who shall be his seed?"

In Mosiah 15:11, he answers the question:

"Behold I say unto you, that whosoever has heard the words of the prophets, yea, all the holy prophets who have prophesied concerning the coming of the Lord--I say unto you, that all those who have hearkened unto their words, and believed that the Lord would redeem his people, and have looked forward to that day for a remission of their sins, I say unto you, that these are his seed, or they are the heirs of the kingdom of God."

Isaiah can be confusing sometimes, and I love when the Book of Mormon prophets explain things.