I was once praying very earnestly to know the time of the coming of the Son of Man, when I heard a voice repeat the following:
“Joseph, my son, if thou livest until thou art eighty-five years old, thou shalt see the face of the Son of Man; therefore let this suffice, and trouble Me no more on this matter.”
I was left thus, without being able to decide whether this coming referred to the beginning of the millennium or to some previous appearing, or whether I should die and thus see his face. I believe the coming of the son of Man will not be any sooner than that time.
(Joseph Smith, February, 1835)
I forgot about this one. Interesting he didn’t know if it was by the return of Christ or death, since it says “IF THOU LIVEST” you will see the face...no death is mentioned.
The quote I was thinking of contained “this generation shall not pass away” or something similar.