Joseph F. Smith (D&C 138)
57 I beheld that the faithful elders of this dispensation, when they depart from mortal life, continue their labors in the preaching of the gospel of repentance and redemption, through the sacrifice of the Only Begotten Son of God, among those who are in darkness and under the bondage of sin in the great world of the spirits of the dead.
No Righteous Man is Ever Taken Before his Time
Joseph Fielding Smith
No righteous man is ever taken before his time. In the case of the faithful Saints, they are simply transferred to other fields of labor. The Lord’s work goes on in this life, in the world of spirits, and in the kingdoms of glory where men go after their resurrection. (The funeral services of Elder Richard L. Evans, Ensign, Dec. 1971, p. 10)