Hadith.5154 - Hammad ibn Uthman narrated from Abu Abdullah (as), who said
"On the Day of Judgment, a man will approach another man and smear him with blood while the people are being held accountable.
The (other) man will say, 'O' servant of Allah (swt), what do I have to do with you?'
The man will reply: 'Did you not assist in my killing on such and such a day with a single word, and thus I was killed?'"