It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: For every soul that is killed unjustly, the first son of Adam (peace be upon him) receives a share of the sin of that blood, because he was the first person who started killing.
Hadith Referenceالفتح الربانی / كتاب خلق العالم / 10314
Hadith Gradingمحدثین:صحیح
Hadith Takhrij«أخرجه البخاري: 3335، 7321، ومسلم: 1677، (انظر مسند أحمد ترقيم الرسالة: 3630 ترقیم بيت الأفكار الدولية: 3630»
Brief Explanation
Benefits: … Since Qabil (Cain) was the one who initiated the crime of unjust killing, therefore, the sin that every murderer will incur, Qabil will also receive a share of it.