1 Nephi 13:24 Textual Variants

and when it proceeded forth from the mouth of a Jew it contained the [ fulneßs 0|planeness 1|plainness ABCDEFGHIJKLMNOPQRS|fulness T] of the gospel of the Lamb

While copying from 𝓞 to 𝓟, Oliver Cowdery accidentally misread scribe 2’s fulneßs as planeness. The 1981 LDS edition restored the original reading. Elsewhere, the text consistently refers to the fullness (never the plainness) of the gospel, even though both are possible:

1 Nephi 10:14 the fullness of the gospel
1 Nephi 15:13 the fullness of the gospel of the Messiah
3 Nephi 16:10 the fullness of my gospel (three times)
3 Nephi 16:12 the fullness of my gospel
3 Nephi 20:28 the fullness of my gospel
3 Nephi 20:30 the fullness of my gospel

Summary: Follow the reading of the original manuscript in 1 Nephi 13:24 (“the fullness of the gospel”); the Book of Mormon consistently refers to the fullness of the gospel, not the plainness.

Analysis of Textual Variants of the Book of Mormon, Part. 1

References