Musannaf Ibn Abi Shayba 33:850

Al-Fadl ibn Dukayn narrated to us, he said: Al-Mughirah ibn Abi al-Hurr narrated to us, from Sa'id ibn Abi Burdah, from his father, from his grandfather, who said: The Messenger of Allah (peace be upon him) came while we were sitting, and he said: "I have never reached a morning except that I sought forgiveness from Allah in it one hundred times."