Sahih Muslim
The Book of Faith (Kitab Al-Iman)
Book Number: 001 / Hadith Number: 114
'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.