Musannaf Ibn Abi Shayba 33:852

Abu Khalid al-Ahmar narrated to us, from 'Awn, from al-Hasan, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Indeed, Allah accepts the repentance of His servant as long as he does not reach the state of *ghargara* (the death rattle)."