The variation in the printer’s manuscript for this example is fairly complex. We do not have the original manuscript here to help us determine the original reading. Oliver Cowdery initially wrote a bominations in the printer’s manuscript, but then he closed up the a with the following bominations and deleted the final s. These corrections appear to be immediate (there is no change in the level of ink flow). The original spacing between the a and bominations suggests that Oliver expected the indefinite article but became confused and initially interpreted abominations as the indefinite article a preceding the “word” bominations. On the other hand, the fact that Oliver originally wrote an s at the end of abomination suggests the opposite—namely, there shouldn’t have been any indefinite article at all!
In any event, Oliver Cowdery ended up correcting the text to read abomination. The 1830 typesetter supplied the indefinite article an. In his editing for the 1837 edition, Joseph Smith changed the number of the verb, from is to are, thus giving the current reading of the text (“whoredoms are an abomination before me”).
There is only one other example where abomination(s) appears as a subject predicate in the Book of Mormon text:
The original manuscript exists, in part, for this text:
these things are a(n )ation in the sight of the Lord
ABOMIN
There is a gap here in the extant leaf. So little of the n for an remains that we cannot be sure that the n isn’t a b. But spacing across the lacuna indicates that the original manuscript probably read an abomination, not simply abomination. Over time Jacob 2:28 has been edited so that now its reading agrees with Alma 39:5 in having the same predicate (namely, “are an abomination”).
When we consider the occurrences of abomination(s) as subject predicate in the King James Bible, we find 32 instances distributed among four possible types (and all fairly frequent). For each type, I list the first instance in the biblical text:
is an abomination 12 times Genesis 43:32
is abomination 8 times Leviticus 18:22
are an abomination 7 times Leviticus 11:13
are abomination 5 times Deuteronomy 22:5
It is worth noting that there are no biblical occurrences of the plural abominations acting as subject predicate, which supports Oliver Cowdery’s correction in 𝓟 of abominations to abomination. The second and fourth types (the two without the indefinite article an) provide direct biblical support for omitting the an before abomination in Jacob 2:28:
Of course, in the original languages (Hebrew and Greek) for all these instances (plus the 20 with the article an, not listed here), no article is expressed, nor is the linking be verb ever there. This means that in all 32 cases of subject predicate abomination, the original language expression is always identical (namely, as “X abomination”), no matter whether the subject X is singular or plural. The English language translators are therefore responsible for selecting the number for the linking verb in these King James examples, and of course they followed the standard rules of subject-verb agreement by always making the be verb agree with the number of the subject. Thus the King James text consistently uses is with singular subjects and are with plural subjects, so there is no direct biblical support for the original singular verb in Jacob 2:28 (“whoredoms is abomination”). Nonetheless, such nonstandard subject-verb agreement is characteristic of the original Book of Mormon text. See the discussion under 1 Nephi 4:4, especially the example from Mosiah 8:19 (“these interpreters was doubtless prepared for the purpose of unfolding all such mysteries”). For a complete discussion, see under subject-verb agreement in volume 3.
Clearly, the King James translators varied in their decision on whether to include the indefinite article before abomination (19 with the an and 13 without); we also get variation in the earliest Book of Mormon text (one with an and one without). For this reason the critical text will follow the earliest textual sources in assigning the reading for Jacob 2:28 (“and whoredoms is abomination before me”) and for Alma 39:5 (“these things are an abomination”). Notice, in particular, the syntactic and semantic similarity between Jacob 2:28 and Deuteronomy 24:4 in the King James text. In each case abomination is postmodified by a prepositional phrase headed by before and both have the singular is and lack the indefinite article an:
Thus there is a striking syntactic and semantic similarity between the two passages, even down to the use of is in both passages. Interestingly, in both cases the subject matter is multiple marriage, with Jacob 2:22–35 dealing with polygyny and Deuteronomy 24:1–4 with divorce and remarriage:
It could well be that the language in Jacob 2:28 draws upon the language of Deuteronomy 24:4, thus supporting Jacob’s use of the precise expression “and whoredoms is abomination before me”.
Summary: Retain in Jacob 2:28 Oliver Cowdery’s corrected reading in the printer’s manuscript: “and whoredoms is abomination before me”; the omitted an before abomination is commonly found in the King James Bible and is supported especially by the reading in Deuteronomy 24:4.