Sahih Muslim
The Book of Destiny (Kitab-ul-Qadr)
Book Number: 033 / Hadith Number: 6408
Sahl b. Sa'd reported it from Allah's Messenger (may peace be upon him) that a person performs deeds like the deeds of the people of Paradise apparently before people and he would be amongst the dwellers of Hell and a person acts apparently like the people of Hell, but (in fact) he would be among the dwellers of Paradise.