The number forty has a number of different symbolic meanings. “In scripture, the number represents a period of trial, testing, probation, or mourning” (Gaskill, Lost Language of Symbolism, 137). Ammon’s group traveled for forty days to assist Limhi’s people, who were in a period of trial, testing, and mourning in their bondage.
The Bible illustrates a related symbol for forty. “In Noah’s time, forty days of rain … made a new beginning for humanity. … Christ fasted forty days before beginning his ministry. … These and other biblical parallels create a typology of deliverance following forty days of tribulation. … When Ammon arrives, Limhi and his people are sunk in despair. … Having suffered greatly and having repented of their sins, they are now rescued” (Larsen, “In His Footsteps,” 94–96).