D&C 42

Concerning death and healing, the Lord revealed - 

"Thou shalt live together in love, insomuch that thou shalt weep for the loss of them that die, and more especially for those that have not hope of a glorious resurrection.

46 And it shall come to pass that those that die in me shall not taste of death, for it shall be sweet unto them;

47 And they that die not in me, wo unto them, for their death is bitter.

48 And again, it shall come to pass that he that hath faith in me to be healed, and is not appointed unto death, shall be healed."  (Doctrine and Covenants 42:45–48)

It becomes apparent in the grand scheme of thing that the time of death for some has already been appointed.  Obviously, the Lord wisdom on death is an eternal perspective.