There was clearly a covenantal relationship between the Savior and the Nephites, but we might ask where the people themselves accepted to do His will by way of covenant? It is not the same as King Benjamin’s speech in which, when he got to the end, all the people at his temple cried with one voice, saying,
Yea, we believe all the words which thou hast spoken unto us; and also, we know of their surety and truth, because of the Spirit of the Lord Omnipotent, which has wrought a mighty change in us, or in our hearts, that we have no more disposition to do evil, but to do good continually (Mosiah 5:2).
These covenants happen at baptism and at the temple, but where in the text of 3 Nephi do we see covenant-making occur? It is during the sacrament. And here they covenant to remember Jesus and the body which he has shown them.
I love to point out that in Bountiful they were not told to partake of the sacrament in remembrance of the broken body alone—they knew that the bread, and the body, had been broken, and they knew what had happened—but more than that, in 18:7 it says, “This shall ye do in remembrance of my body, which I have shown unto you.” The resurrected Lord was offering the sacrament right then, in person. That sacrament was a token of the resurrected reality of the tangible body of Jesus with which he had risen from the dead and ascended to heaven.
When we pick up the bread to partake of the sacrament, we often think of how painful it must have been for his body to have been broken, but the substance of the bread also is tangible material that symbolizes the physical nature of the resurrected body. As people partake of the bread, they are symbolically touching the Lord’s body, just as the people at Bountiful did as they came forward one by one to ascertain the truthfulness of the resurrection and to know the literalness of Jesus’ being there with a body containing the marks of his death. They could testify with certainty that He had overcome suffering and death.
It is indeed a blessing to have access to both the sacrament of the Last Supper, which was the sacrament of the suffering and death of the Lord, and the sacrament in 3 Nephi, which is the sacrament of the Lord’s resurrected body. Just as the Bible and Book of Mormon go hand in hand, the Latter-day sacrament symbolizes both the broken body of the Last Supper and the risen body that the Savior revealed to the Nephites.