Fewer words version: The Lord said to me, “Since they [Laman, Lemuel, and their followers] won’t obey you, they’ll be cut off from my presence.” And he cursed them by changing their white, exceedingly fair and delightsome skin into a skin of blackness so they would no longer appeal to my people.
Wherefore, the word of the Lord was fulfilled which he spake unto me, saying that: Inasmuch as they will not hearken unto thy words they shall be cut off from the presence of the Lord. And behold, they were cut off from his presence. And he had caused the cursing to come upon them, yea, even a sore cursing, because of their iniquity. For behold, they had hardened their hearts against him, that they had become like unto a flint; wherefore, as they were white, and exceedingly fair and delightsome, that they might not be enticing unto my people the Lord God did cause a skin of blackness to come upon them. 2 Nephi 5:20
