Internal consistency alert, from 2 Nephi 26:

7 O the pain, and the anguish of my soul for the loss of the slain of my people! For I, Nephi, have seen it...

He saw it in 1 Nephi 12.

Compare 2 Nephi 26:10

10 And when these things have passed away a speedy destruction cometh unto my people; for, notwithstanding the pains of my soul, I have seen it; wherefore, I know that it shall come to pass; and they sell themselves for naught; for, for the reward of their pride and their foolishness they shall reap destruction; for because they yield unto the devil and choose works of darkness rather than light, therefore they must go down to hell.

...with 1 Nephi 12:16-19

16 And the angel spake unto me, saying: Behold the fountain of filthy water which thy father saw; yea, even the river of which he spake; and the depths thereof are the depths of hell.
17 And the mists of darkness are the temptations of the devil, which blindeth the eyes, and hardeneth the hearts of the children of men, and leadeth them away into broad roads, that they perish and are lost.
18 And the large and spacious building, which thy father saw, is vain imaginations and the pride of the children of men. And a great and a terrible gulf divideth them; yea, even the word of the justice of the Eternal God, and the Messiah who is the Lamb of God, of whom the Holy Ghost beareth record, from the beginning of the world until this time, and from this time henceforth and forever.
19 And while the angel spake these words, I beheld and saw that the seed of my brethren did contend against my seed, according to the word of the angel; and because of the pride of my seed, and the temptations of the devil, I beheld that the seed of my brethren did overpower the people of my seed.