Sahih Muslim
The Book Pertaining to the Turmoil and Portents of the Last Hour (Kitab Al-Fitan wa Ashrat As-Saah)
Book Number: 041 / Hadith Number: 7055
Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: Between the two blowiings of the trumpet (there would be an interval of forty). They said: Abu Huraira, do you mean forty days? He said: I cannot say anything. They said: Do you mean fortv months? He said: I cannot say anything They said: Do you mean forty years? He said: I cannot say anything. Then Allah would cause the water to, descend from the sky and they (people) will sprout like vegetable The only thing in a man which would not decay would be one bone (spinal chord) from which the whole frame would be reconstituted on the Day of Resurrection.