The Book Pertaining to the Turmoil and Portents of the Last Hour (Kitab Al-Fitan wa Ashrat As-Sa`ah)
Muslim :: Book 41 : Hadith 7051
Anas reported that a person asked Allah's Messenger (may peace be upon him) as to when the Last Hour would come. He had in his presence a young boy of the Ansar who was called Mabammad. Allah's Messenger (may peace be upon bion) said: If this young boy lives. he may not grow very old till (he would see) the Last Hour coming to you.