An elderly Sahabiyyah (RA, a female companion) went to visit Aishah (RA)and Rasulullah (PBUH). She asked the Prophet (PBUH),"Please pray to Allah to bless me with Paradise" Allah's Messenger (PBUH) told her humourously, "But old people will not enter Paradise".
The old woman was too shocked to ask Rasulullah (PBUH) why and he left for the mosque for prayers. The Sahabiyyah sat thinking that the Prophet (PBUH) meant old people would go to Hell; so she started crying and wailing. Aishah tried to console her, but she would not stop crying.
On his return, Aisha (RA) told him that the old woman had been crying. Then Allah's Prophet (PBUH) explained "But Allah will make the old people young again before he sends them to Paradise".
She smiled and replied "Returning me to the physical appearance of my youth would be one of Allah's greatest Mercies." (Islam - The Natural Way)