One of the oldest debates with regard to the Sermon on the Mount revolves around the issue of Christ's audience. Some argue that the entire sermon was given to the Twelve in preparation for their ordination to the apostleship. Others argue that the sermon was given to the entire multitude and therefore applies to every disciple of Christ. Significantly, then, the Savior defined his audience for the rest of chapter 13. It was to the chosen twelve in Bountiful to whom he was speaking when he said, take no thought for your life, what ye shall eat, or what ye shall drink. These words are especially appropriate for a witness of Christ who is required, as a missionary, to preach without purse or scrip.
Even though the next several verses were addressed to the twelve disciples, we should also apply them, in context, to ourselves. This is the lesson we learn from Nephi, Now these are the words, and ye may liken them unto you and unto all men (2 Nephi 11:8).
Jeffrey R. Holland
"In a general sense these verses can apply to all believers, but at their most literal level they apply to those the Lord has called as his full-time witnesses. Most people must give some thought to what they will eat and what they will wear; the necessities of life require it. But the twelve disciples were not to do so, for they were chosen "to minister unto [the] people." Their call was to give complete devotion to their spiritual ministry and to trust in God's—and the people's—providence for their temporal needs." (Christ And The New Covenant, p. 265)