Sayyiduna Abu Darda (may Allah be pleased with him) narrates: I heard the Prophet (peace and blessings of Allah be upon him) say: "For every sin (there is hope) that Allah Almighty will forgive it, except for the person who dies as a polytheist or the one who has intentionally killed a believer."
Hadith Referenceصحیح ابن حبان / كتاب الجنايات / 5980
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - «الصحيحة» (511).فضيلة الشيخ العلّامة شُعيب الأرناؤوطحديث صحيح