This section of the Sermon on the Mount has a parallel section in Luke 12:22–29, where very similar sayings are presented with some differences. They either depend on the same source, or perhaps these sayings were passed along in the early communities and the oral tradition became the source for both, accounting for the slight differences.
Old World Context: The command to “take no thought” means that one should not be anxious about such things. This section follows closely after that describing treasures susceptible to moth and worm (clothing and food). The instruction is not to stop working but rather to not be concerned with their quantity (and especially not with their rich quality) because of the greater importance attached to heavenly treasures. This section begins with “therefore,” signaling that it summarizes the lesson to be drawn from the previous instructions. The lesson in this case is certainly not that we should be idle but that we should not be overly concerned with food and clothing.
An additional aspect of the Old World context was the relationship between the poor who listened to Jesus and the rich who controlled access to the world’s goods. The poor had no mechanism whereby they could change their status. While they certainly could, and did, wish it were different and they were the rich ones, nevertheless, they were in a condition that precluded access to the highest social class that held the wealth. In this context of hopelessness of changing their social condition, they are told that they must accept what is “natural” to this world and do their best within it. Hence see the contrasts of the Beatitudes. In particular, we find the interesting statement (v. 27 below): “Which of you by taking thought can add one cubit unto his stature?” No amount of worrying or wishing can change the natural condition of height. No amount of worrying or wishing can change their social condition.
Book of Mormon Context: A lesson that dissuaded hearers to pay too much attention to clothing would have been particularly apt in the New World setting where the beginnings of apostasy were frequently introduced by “costly apparel.” (See commentary accompanying Alma 1:6.)
Text: In addition to a chapter break here (but not in the King James Version), a textual addition creates a new social context for the next set of verses. In the Book of Mormon, Jesus specifically addresses the twelve disciples for the next section (vv. 25–33). This shift in audience solves the problem of apparently counseling the audience not to work for a living. By restricting this commandment to the twelve, the context becomes missionary work, to do which the twelve were to go forth without purse or scrip. (See also commentary accompanying 3 Nephi 13:11.)
This insertion is only temporary, since Jesus immediately readdresses the multitude (3 Ne. 14:1). Although this insertion describes Jesus’s actions in the New World, the context is clearly the New Testament; therefore, it is best to see this insertion as one of Joseph Smith’s numerous interactions with his source. In the Joseph Smith Translation, Joseph still uses missionary work as the context but applies the instructions to all disciples:
And, again, I say unto you, Go ye into the world, and care not for the world; for the world will hate you, and will persecute you, and will turn you out of their synagogues.
Nevertheless, ye shall go forth from house to house, teaching the people; and I will go before you.
And your heavenly Father will provide for you, whatsoever things ye need for food, what ye shall eat; and for raiment, what ye shall wear or put on. (JST Matt. 6:25–27)
Frank F. Judd Jr., assistant professor of ancient scripture at Brigham Young University, reads the whole of the Sermon on the Mount as missionary instructions to the twelve:
The entirety of the Sermon on the Mount was directed toward the “disciples,” with a “multitude” of others apparently within earshot, whereas the Sermon at the Temple [in 3 Nephi] was directed toward all disciples generally, with the exception of a few verses that were directed toward the Twelve specifically. Thus, we would not be quite accurate in calling the Sermon on the Mount “apostolic preparation” as some have suggested. Though it contains important instructions for Apostles, it is more generally “missionary preparation” than primarily “apostolic preparation.”