5 ¶ Behold, I willsend• youElijah• the prophetbefore• the coming of the great• and dreadfulday• of the LORD:
6 And he shallturn the heart• of thefathers to thechildren, and the heart of thechildren to their fathers, lest I come andsmite• theearth with acurse.
APR 3 1836KIRTLAND TEMPLE
D & C 110:
13 After this vision had closed, another great and gloriousvision burst upon us; forElijah• the prophet, who was taken to heaven without tasting death, stood before us, and said:
14 Behold, the time has fully come, which was spoken of by the mouth of Malachi—testifying that he [Elijah] should be sent, before the great and dreadful day of the Lord come—
15 To turn• thehearts of the fathers to the children, and the children to the fathers, lest the whole earth be smitten with a curse—
16 Therefore, the ( added) (sealing power) keys of thisdispensation are committed into your hands; and by this ye may know that the great and dreadfulday• of the Lord is near, even at the doors
17- Temple Work and the Millennium
Salvation can not be gained except through baptism of water and the spirit, nor can exaltation be achieved except through temple endowments and the sealing of families together for eternity.These saving and exalting ordinances are performed vicariously in temples for the worthy dead who did not have the opportunity to receive them in this life.We are commanded to go with our might, collect all the accurate genealogical data we can, and perform these saving and exalting ordinances for our worthy ancestors.Obviously, due to the frailties, incapacities, and errors of mortal men, and because the records of past ages are often scanty and inaccurate, this great work can not be completed for every worthy soul without assistance from on high.
The millennial era is the time primarily, when this assistance will be given by resurrected beings.
Genealogical records unknown to us will then become available.Errors committed by us in sealings or other ordinances will be rectified, and all things will be arranged in proper order.Temple work will be the great work of the millennium.
Joseph Fielding Smith- Doctrines of Salvation Vol. 2 P.P. 251-252