3 Nephi 18
The only message that the Savior spoke to all the people in this chapter is that they should pray for those who meet with them but are not part of the church as yet and should not cast any from their midst. To the apostles He teaches that they shall administer the sacrament and that the Sacrament was not to go to those who were not worthy of such a covenant.
I also notice that the Savior left while the people were overshadowed by a cloud.