Musannaf Ibn Abi Shayba 33:1415

Abu Usama narrated to us, from Abu al-Ashhab, from al-Hasan, who said: The servant remains in goodness as long as he does not commit a major sin that corrupts his heart and his intellect for him. He said: And al-Hasan said: Faith, faith; for whoever is a believer, he has intercessors before Allah whose intercession is accepted.