“Here is one of the most important single-line teachings in all of scripture. … If we want to feel real love toward God and toward other persons, we must bridle our passions or emotions. A bridle does not suppress the spirited creature (whether horse or human) but is used to control or direct. [Alma] did not say eliminate or even suppress your passions, but to bridle them—harness, channel, and focus them. Why? Because discipline makes possible a richer, deeper love” (Ogden and Skinner, Book of Mormon, 2:33).
The superscription to Alma 39 was part of the ancient record translated by the Prophet Joseph Smith and dictated by him to his scribe (see also, for example, 2 Nephi, Mosiah 9, and Helaman).
The italicized words “Comprising chapters 39 through 42” were not part of the ancient record but were added later to printed editions of the Book of Mormon.