Musannaf Ibn Abi Shayba 21:324

Ghundar narrated to us, from Shu'bah, from 'Amr ibn Murrah, from Abu Burdah, who said: I heard al-Agharr—and he was one of the companions of the Prophet, may Allah bless him and grant him peace—narrating to Ibn 'Umar. He said: The Messenger of Allah, may Allah bless him and grant him peace, said: "Repent to your Lord, for indeed I repent to Him one hundred times a day."