Musnad Ahmad 27:1948

Sulayman ibn Dawud narrated to us, Abd al-Rahman ibn Thabit informed us, my father narrated to me, from Makhul, from Jubayr ibn Nufayr, from Ibn Umar, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, Allah the Exalted accepts the repentance of His servant as long as he does not reach the death rattle."