Sahih Bukhari Volume 003, Book 043, Hadith Number 621.

Narated By Safwan bin Muhriz Almazini : While I was walking with Ibn 'Umar holding his hand, a man came in front of us and asked, "What have you heard from Allah's Apostle about An-Najwa?" Ibn 'Umar said, "I heard Allah's Apostle saying, 'Allah will bring a believer near Him and shelter him with His Screen and ask him: Did you commit such-and-such sins? He will say: Yes, my Lord. Allah will keep on asking him till he will confess all his sins and will think that he is ruined. Allah will say: 'I did screen your sins in the world and I forgive them for you today', and then he will be given the book of his good deeds. Regarding infidels and hypocrites (their evil acts will be exposed publicly) and the witnesses will say: These are the people who lied against their Lord. Behold! The Curse of Allah is upon the wrongdoers." (11.18)