The most obviously spectacular part of this story is the effectual prayer of Nephi and the resulting bursting of the bands. From this long distance in time, that appears to be fairly clearly a miracle. However, verse 19 clearly indicates that in the context of the moment, it was not considered particularly divine. Nephi has allowed that he was large of stature, and the bursting of the bonds may have been taken by Laman and Lemuel as nothing more than a demonstration of Nephi's strength (or their own ineptitude in tied knots).
Verse 19 also points out a fascinating developing dynamic in the Lehite party. When Laman and Lemuel continue their deadly designs upon Nephi, it is the family of Ishmael which prevails upon them to cease. These events are taking place on the road back from convincing Ishmael and his family to come with Lehi and his family. They have not yet returned to Lehi's camp (1 Nephi 7:21-22).
Whatever it took to impress Ishmael's family to come on the journey, it must have been singularly difficult to be so soon on this long journey, and to find themselves in the midst of a violent intra-family dispute. That they not only mediated this altercation, but continued on the journey speaks untold volumes about the strength of the witness they received from the Lord to go on the journey (1 Nephi 7:5).