Sahih Muslim Book 1, Hadith Number 114.

Chapter : Concerning the peculiarities of a hypocrite.

‘Uqba b. Mukarram al-‘Ami reported that he heard ‘Ala’ b. ‘Abdur-Rahman narrating this hadith with this chain of transmitters and he said: Three are the signs of a hypocrite, even if he observed fast and prayed and asserted that he was a Muslim.