This segment of the Sermon on the Mount (or, as it is known for the New World, the Sermon at the Temple), ends with the declaration that Jesus has taught the people essential information on how to follow him. If they do as he has taught, they will be as a house built on a firm foundation.
Since he has also discussed the idea that there might be counterfeit gospels, he also notes that if they do not follow his instructions, they would be on a sandy foundation that cannot hold up. The counterfeit gospels, even those who call his name, do not have the power to build a firm foundation of faith that will lead to eternal life.
The 1830 edition of the Book of Mormon ends a chapter at this point.