Sahih Muslim | Book 30 | Hadith Number 5674
Narrated by Abu Huraira
Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: The similitude of mine and that of the Apostles before me is that of a person who built a house quite imposing and beautiful and he made it complete but for one brick in one of its corners. People began to walk round it, and the building pleased them and they would say: But for this brick your building would have been perfect. Muhammad (may peace be upon him) said: And I am that final brick.