General Douglas MacArthur once stated that old soldiers never die, they just fade away. A similar statement could be made about some great prophets, “they never die, they just walk away.” Alma…departed out of the land [and] was never heard of more, Moses went up mount Nebo where the Lord took Moses unto himself (Alma 45:19, Deut 32:49-50), and Nephi departed out of the land, and whither he went, no man knoweth. For the righteous, death is not bitter, for those that die in me shall not taste of death, for it shall be sweet unto them (DC 42:46). This is especially true for these prophets who were apparently taken up by the Lord without even tasting death. Others that were translated in this manner include Elijah (2 Kgs 2:11, DC 110:13), Enoch, and his people (Gen 5:24, DC 38:4; DC 107:49).
Joseph Smith
"Now the doctrine of translation is a power which belongs to this Priesthood. There are many things which belong to the powers of the Priesthood and the keys thereof, that have been kept hid from before the foundation of the world; they are hid from the wise and prudent to be revealed in the last times.
“Many have supposed that the doctrine of translation was a doctrine whereby men were taken immediately into the presence of God, and into an eternal fullness, but this is a mistaken idea. Their place of habitation is that of the terrestrial order, and a place prepared for such characters He held in reserve to be ministering angels unto many planets, and who as yet have not entered into so great a fullness as those who are resurrected from the dead…This distinction is made between the doctrine of the actual resurrection and translation: translation obtains deliverance from the tortures and sufferings of the body, but their existence will prolong as to the labors and toils of the ministry, before they can enter into so great a rest and glory.” (Teachings of the Prophet Joseph Smith, p. 170)