Dan Wood suggests (personal communication, 15 November 2003) that the word nevertheless seems out of place here. One possible replacement would be the word therefore (or perhaps wherefore):
Even so, there are no instances in the text where nevertheless has ever been mixed up with either therefore or wherefore.
Perhaps the meaning here is the disciples didn’t intend to cease praying, so that Jesus didn’t really need to tell them to continue praying, but he still did. One may protest that Jesus wouldn’t ask them to do something that he knew they would continue to do anyway. Yet arguments from God’s omniscience may not be appropriate for the Book of Mormon text. For instance, at the beginning of 3 Nephi 17, Jesus first tells the Nephites that he must leave, but then he changes his mind when he sees their great desire for him to stay longer (3 Nephi 17:1–8). One can reinterpret the text in 3 Nephi 17 to claim that Jesus already knew he would be staying longer even when he said that he had to leave and the Nephites needed to go home to ponder what he had already said. I would prefer to think that through faith we can sometimes change the Lord’s mind. In fact, there is evidence from 3 Nephi 16–17 that Jesus cut off his discourse on Isaiah 52:8–10 right after quoting it because he could tell that his audience’s attention was lagging (see the discussion under 3 Nephi 16:17–18). Thus here in 3 Nephi 19:26, Jesus asked the disciples to continue praying without knowing whether they actually intended to keep on praying.
Another possibility here, one less fraught with theological implications, is that the meaning of the word nevertheless may be different than what we expect in today’s English. The Oxford English Dictionary under definition 5b of never indicates that in Middle English and Early Modern English phrases like “never the less” acted as a negative emphatic with the meaning ‘not in any way less’ or ‘by no means less’. In other words, the word nevertheless here in 3 Nephi 19:26 may mean something like ‘by no means’ or ‘not at all’, so that in context the negative clause could be interpreted as equivalent to “and by no means did they cease to pray”. This interpretation may very well represent what the original sentence intended to convey.
David Calabro (personal communication) points out other possible interpretations that may work here. For instance, Jesus’s counsel for them to continue praying did not nevertheless interrupt their praying. In other words, the word nevertheless may be negating only one aspect of the clause “they did not cease to pray” rather than every aspect of the clause. To be sure, the reading here in 3 Nephi 19:26 is a difficult one; but the use of the word nevertheless does appear to be intended and will therefore be retained in the critical text.
Summary: Maintain in 3 Nephi 19:26 the use of nevertheless; the meaning here seems to be an emphatic negative with the meaning ‘and by no means’, but it is also possible to interpret the word nevertheless as negating only some restricted aspect of the clause “they did not cease to pray”.