The resolution of this incident is all too brief for those who would like to reconstruct what happened. To whom did the Lord speak? If he spoke directly to Laman and Lemuel, that would be tremendous indeed, and raise other questions as to why the Lord would so openly speak with those sinners in the midst of their worst sinning to date (plotting the death of their father and brother)? Did the Lord speak through Lehi or Nephi again - both of whom who had been capable of calling those recalcitrants to repentance? It is not said.
Nephi says only that they were chastened of the Lord. It appears that the Lord did so directly, but there is still room to see that as the words of the Lord through a mouthpiece. Regardless, they were sufficiently chastised.
The final verse provides a little more information that might be lost in the murmurings and plottings. Once again hunger may have had some play, as their repentance leads directly to "the Lord did bless us again with food, that we did not perish." Perhaps this outbreak, while initiated through the death of Ishmael, was exacerbated by the lack of food after the journeying, precisely as was the murmuring of the last stop.