Musannaf Ibn Abi Shayba 21:328

Ibn ‘Ulayyah narrated to us, from Yunus, from Humayd ibn Hilal, from Abu Burdah, who said: I sat with an old man from the companions of the Messenger of Allah, may Allah bless him and grant him peace, in the mosque of Kufa. He narrated to me and said: I heard the Messenger of Allah, may Allah bless him and grant him peace—or he said: The Messenger of Allah, may Allah bless him and grant him peace, said: "O people, repent to Allah and seek His forgiveness, for I repent to Allah and seek His forgiveness one hundred times every day." I said: "O Allah, I seek Your forgiveness twice." He said: "It is what I am telling you."