1 Nephi 2:18

18 But, behold, Laman and Lemuel would not hearken unto my words; and being grieved because of the hardness of their hearts I cried unto the Lord for them.

Nephi feels grieved because his brothers are rejecting his testimony. As recorded in the scriptures, grief, or at least the kind of grief this verse refers to, is triggered by rejection of testimony or resistance to conversion. This is founded in love or concern for a person’s (adversary’s) salvation. It also seems to be a call to action. If nothing else, it is a call to pray for their souls, as Nephi did here.