Musannaf Ibn Abi Shaybah

Hazrat Ibn Umar (may Allah be pleased with them both) narrates that we used to count these words spoken by the Messenger of Allah (peace and blessings be upon him) in one gathering, and they would be one hundred times: O my Lord! Forgive me, and accept my repentance. Surely, You are the Acceptor of repentance and the Most Forgiving.