Musnad Abu Ya'la al-Mawsili 1:12

Abu Khaythama narrated to us, Waki’ ibn al-Jarrah narrated to us, Mis’ar and Sufyan narrated to us, from ‘Uthman ibn al-Mughira al-Thaqafi, from ‘Ali ibn Rabi’a al-Walibi, from Asma’ ibn al-Hakam al-Fazari, from ‘Ali, who said: "When I heard a hadith from the Messenger of Allah (may Allah bless him and grant him peace), Allah would benefit me with it as He willed. And when someone else narrated it to me from him, I would make him swear an oath; if he swore to me, I would believe him. Abu Bakr narrated to me—and Abu Bakr spoke the truth—that he (may Allah bless him and grant him peace) said: 'There is no one who commits a sin, then performs ablution and perfects the ablution'—Mis’ar said: 'Then he prays'—Sufyan said: 'He prays two rak'ahs, then seeks forgiveness, except that he is forgiven.'"