The Book of Faith (Kitab Al-Iman)
Muslim :: Book 1 : Hadith 112
It is reported on the authority of Abu Huraira that the Messenger of Allah (may peace and blessings be upon him) said: Three are the signs of a hypocrite: when he spoke he told a lie, when he made a promise he acted treacherously against it, when he was trusted he betrayed.