Sahih Bukhari Volume 008, Book 077, Hadith Number 602.
Narated By 'Ali : While we were sitting with the Prophet who had a stick with which he was scraping the earth, he lowered his head and said, "There is none of you but has his place assigned either in the Fire or in Paradise." Thereupon a man from the people said, "Shall we not depend upon this, O Allah's Apostle?" The Prophet said, "No, but carry on and do your deeds, for everybody finds it easy to do such deeds (as will lead him to his place)." The Prophet then recited the Verse: 'As for him who gives (in charity) and keeps his duty to Allah..." (92.5)