Sahih Muslim Book 2, Hadith Number 445.

Chapter : The merit of Wudu and that of prayer after it.

Jami’ b. Shaddad reported: I heard Humran b. Aban narrate to Abu Burda in this very mosque during the governorship of Bishr that ‘Uthman b. Alfan said: The Messenger of Allah (may peace be upon him) observed: He who completed ablution as Allah, the Exalted, enjoined upon him, his obligatory prayers would be expiatious (for his minor sins that he would commit) during (the interval) between them. This Hadith is transmitted by Ibn Mu’adh, and in the Hadith narrated by Ghundar, the words “during the governorship of Bishr” are omitted and there is no mention of the obligatory prayers.