'Amr ibnul 'Aas Radiyallahu 'Anhu reports:
"(Rasulullah Sallallahu 'Alayhi Wasallam gave attention, spoke and showed love to the worst person of a nation. So that, the person may feel he is being given special attention). He used to give attention, and spoke to me also in a manner, that I began to feel that I was the best among the community. (Therefore one day) I asked: 'O Messenger of Allah, am I better or is Abubakr better?' He replied: 'Abubakr'. I then asked: 'Am I better, or 'Umar?' He replied. "Umar'. I asked: 'Am I better or 'Uthmaan?' He replied: 'Uthmaan'. When I asked him these questions, Rasulullah Sallallahu 'Alayhi Wasallam told me the truth. (He did not tell me I was better to keep me happy. Afterwards I felt ashamed of myself on this deed). I felt I should not have asked such a question".
English reference: Book 47, Hadith 327
Arabic reference: Book 48, Hadith 344