Hadith Qudsi Number 033 : The Authority Of Abu Hurayrah

The Prophet (peace be upon him), from among the things he reports from his Lord (mighty and sublime be He), is that he said : "A servant [of Allah's] committed a sin and said: O Allah, forgive me my sin. And He (glorified and exalted be He) said: My servant has committed a sin and has known that he has a Lord who forgives sins and punishes for them. Then he sinned again and said: O Lord, forgive me my sin. And He (glorified and exalted be He) said: My servant has committed a sin and has known that he has a Lord who forgives sins and punishes for them. Then he sinned again and said: O Lord, forgive me my sin. And He (glorified and exalted be He) said: My servant has committed a sin and has known that he has a Lord who forgives sins and punishes for sins. Do what you wish, for I have forgiven you."

Reporters.
It was related by Muslim (also by al-Bukhari).