It is narrated from Sayyiduna Mu'awiyah (may Allah be pleased with him), and he used to narrate very few hadith from the Messenger of Allah (peace and blessings be upon him), that the Messenger of Allah (peace and blessings be upon him) said: "It is hoped that every sin will be forgiven, except that a man dies while he is a disbeliever or kills a believer deliberately."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 16906