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: 7050
'A'isha reported that when the desert Arabs came to Allable Messenger (may peace be upon him) they asked about the Last Hour as to when that would come. And he looked towards the youngest amongst them and said: If he lives he would not grow very old that he would find your Last Hour coming to you the would see you dying).