The Book Giving Description of the Day of Judgement, Paradise and Hell (Kitab Sifat Al-Qiyamah wa'l Janna wa'n-Nar)
Muslim :: Book 39 : Hadith 6770
A'isha, the wife of Allah's Apostle (may peace be upon him), reported that Allah's Messenger (may peace be upon him) used to say: Observe moderation (in doing deeds), and if yciu fail to observe it perfectly, try to do as much as you can do (to live up to this ideal of moderation) and be happy for none would be able to get into Paradise because of his deeds alone. They (the Companions of the Holy Prophet) said: Allah's Messenger, not even thou? Thereupon he said: Not even I, but that Allah wraps me in His Mercy, and bear this in mind that the deed loved most by Allah is one which is done constantly even though it is insignificant.