First Nephi 10
The context of Lehi leaving Jerusalem was that he was part of the "scattering" of the house of Israel. He knew this, and taught it to his children. In fact, Lehi wasn't the first to be broken off from the tree of Israel. This scattering had been prophesied by prophets of old and his fulfillment of those prophesies gave him great perspective. His teachings focused on the ultimate remedy of the scattering: gathering. This is fortunate for us who read it, because we are living in the time of the gathering.