I go and do the things which the Lord hath commanded, for I know that the Lord giveth no unto the children of men, save he shall a way for them that they may accomplish the thing which he commandeth them.Only 8 verses later, Nephi repeats the last part of it
But behold I said unto them that: the Lord liveth, and as we live, we will not go down unto our father in the wilderness until we have the thing which the Lord hath commanded us.Nephi's mother repeats it in 1 Nephi 5:8
I also know of a surety that the Lord hath protected my sons, and delivered them out of the hands of Laban, and given them power whereby they could the thing which the Lord hath commanded them.The only difference is "given them power" instead of "prepared a way". A variant of this theme in 1 Nephi 9:6
But the Lord all things from the beginning; wherefore, he prepareth a way to accomplish all his works among the children of men;Not only the thing which he has commanded but "all his works". Again, in 1 Nephi 17:3
And if it so be that the children of men keep the commandments of God he doth nourish them, and them, and provide means whereby they can accomplish the thing which he has commanded them"Provide means", "give them power" or "prepare a way". These are just different wordings of the same fundamental principle that Nephi is really eager to convey to his readers and demonstrate how it has applied to his life.