Abu Dawud Book 30, Hadith Number 4228.
Chapter : Fitan and their predictions.
Narated By Hudhaifah : The Apostle of Allah (PBUH) stood among us (to give an address) and he left out nothing that would happen up to the last hour without telling it. Some remembered it and some forgot, and these Companions his have known it. When something of it which I have forgotten happens, I remember it, Just as a man remembers another’s face when he is away and recognises him when he sees him.