Isaiah 51:23 (King James Bible) but I will put it into the hand of them that afflict thee which have said to thy soul bow down that we may go over
Contextually, the original reading of the printer’s manuscript (“which I said to thy soul”) does not make much sense since quite obviously it is Israel’s afflicters, not the Lord, who said “bow down that we may go over”. Further, for this earliest reading in 𝓟, there is no way to determine how the relative pronoun which connects into the following clause; the direct object of the verb said is the following direct quote (“bow down that we may go over”). Thus which ends up having no antecedent as well as being disconnected from its own relative clause.
The 1830 compositor set this anomalous phraseology, but Joseph Smith, in his editing for the 1837 edition, corrected the I to have. He may have made this correction by referencing a copy of the King James Bible. He also edited the which to who, showing that he correctly interpreted the original which as referring to people. For further discussion of the editing of which to who, see which in volume 3.
The original manuscript is not extant for 2 Nephi 8:23. The accidental replacement of have with I seems quite impossible from a visual point of view, so it is doubtful that the I entered the text as Oliver Cowdery copied from 𝓞 into 𝓟. A more reasonable possibility is that Oliver misinterpreted this passage as he wrote down Joseph Smith’s dictation in 𝓞. In normal speech, the h of the helping verb have would have been silent; thus Joseph would have probably dictated “which have said” as /wIcˇ ßv sed/. The voiced fricative /v/ could have been articulatorily assimilated and partially devoiced in the context of the following voiceless fricative /s/, thus making it more diffi- cult for Oliver to hear the /v/ as distinct from the following /s/. Further, the schwa vowel /ß/ could have been interpreted as the initial part of the diphthong /ai/, which was frequently pronounced as /ßi/ in earlier dialects of English (and is still pronounced this way in some dialects today). In other words, the rapid pronunciation of /wIcˇ ßv sed/ could have been misinterpreted as “which I said”. In addition, the earlier dictation of the subject pronoun I (in the preceding clause “I will put it into the hand of them”) could have primed Oliver to mishear the /ßv/ as I.
Summary: Follow Joseph Smith’s restoration of the King James phraseology “which have said” in 2 Nephi 8:23; the earliest textual source (“which I said”) seems to be the result of Oliver Cowdery mishearing “which have said” as he took down Joseph’s dictation.