Musannaf Ibn Abi Shayba 21:209

Yazid ibn Harun narrated to us, from Muhammad ibn Muslim, from Amr ibn Dinar, from Ubayd ibn Umayr, who said: We used to consider the *awwab* (the one who frequently returns to Allah) to be the *hafiz* (the one who guards his speech/actions) if, when he stood up from his gathering, he said: "O Allah, forgive me for what I committed in this gathering of mine."