The previous comments ended with 1 Nephi 3:6, and this one begins with that same verse. The reason is that it is a transition in the story. It provides the literary concluding contrast between the murmuring brothers and the not-murmuring Nephi.
It is a transition because there is an important literary connection between: “therefore go, my son” in verse 6 and Nephi’s reply in verse 7 that: “I will go and do.” The literary parallelism continues with the statement in verse 6 that Nephi shall be favored of Jehovah because he hasn’t murmured. Then, in verse 8, the literary unit is completed when Lehi is glad: “for he knew that [Nephi] had been blessed of the Lord.”
Beyond the literary structures, Nephi’s statement that “I will go and do the things which the Lord hath commanded” becomes a leitmotif throughout the book of 1 Nephi. Nephi will be shown doing things. There is an implicit contrast between the murmuring, which is a vocal indication, and the doing, which is a physical manifestation. Nephi sets up the subtle contrast between what one might say, and the more important contrast with what they do. Even when the brothers are more positive in what they say, they cannot sustain the good sayings. They will return to murmuring, and to not doing what Jehovah requires.
Modern readers are comforted by Nephi’s declaration that when we are doing God’s commandments, that we may be assured that they are possible. God will not require anything of us that we cannot accomplish. That does not mean that everything will be easy. Lehi will later teach an important sermon on the necessity of opposition in all things. At this early point, however, Nephi reminds us that opposition does not mean impossibility.