Sahih Muslim
The Book Pertaining to Repentance and Exhortation to Repentance (Kitab Al-Tauba)
Book Number: 037 / Hadith Number: 6643
Abu Huraira reported lie heard Allah's Messenger (may peace be upon him) as saying that a servant committed a sin. The rest of the hadith is the same, but there is a slight variation of wording.