Isaiah 29:13 (King James Bible) forasmuch as this people draw near me with their mouth and with their lips do honor me but have removed their heart far from me and their fear toward me is taught by the precept of men …
Here the 1830 typesetter pluralized two words, heart and precept. The original text of the Book of Mormon, as reflected in the printer’s manuscript, agrees with the King James text, which has the singular for these two words (as does the Masoretic Hebrew text).
One could argue that the plural hearts makes more sense since each person has one heart and we are talking about many persons (“this people”). Yet the 1830 typesetter did not change mouth to mouths in this verse, so this pluralization does not seem to be consistently applied. The Hebrew text for this passage consistently assigns to “this people” the singular or plural according to whether the individual person has singular or plural forms of these parts of the body (“their mouth”, “their lips”, “their heart”). The King James Bible and the original Book of Mormon text also follow this consistent usage here in 2 Nephi 27:25. But in other places in the Isaiah quotations, the earliest Book of Mormon reading frequently does use plural forms for parts of the body rather than the singular forms found in the corresponding Isaiah passages in the King James Bible. See the example of tongue(s) under 2 Nephi 13:8–9 and eye(s) under 2 Nephi 23:18.
In English usage, the plural “the precepts of X” is consistently more frequent than the singular “the precept of X”. The Oxford English Dictionary, for instance, lists 67 instances of “precepts of X” but 29 of “precept of X”. The ratio of comparison is about the same in current English, as exemplified by the statistics found on for 4 June 2004: namely, 99,600 instances of “precepts of X” and 40,700 of “precept of X”. Both historically and currently, the plural is over two times more frequent than the singular. It is therefore not surprising that the 1830 compositor accidentally set the plural “the precepts of men”.
The rest of the Book of Mormon text consistently uses the plural “precepts of men”, with three occurrences in the next chapter; in each of these cases the printer’s manuscript (here the earliest extant text) reads in the plural:
Thus only in a direct quote of Isaiah does the earliest text have the singular “the precept of men”.
Summary: Restore in 2 Nephi 27:25 the singulars heart and precept, in accord with the reading of the printer’s manuscript as well as the King James Bible.