Sunan Ibn Majah, Chapter: The Chapters on Blood Money

"A man killed (another) during the time of the Messenger of Allah (saw) and was referred to the Prophet (saw). He handed him over to the victim's next of kin, but the killer said: 'O Messenger of Allah (saw), by Allah I did not mean to kill him.' The Messenger of Allah (saw) said to the next of kin, 'If he is telling the truth and you kill him, you will go to Hell.' So he let him go. He had been tied with a rope, and he went out dragging his rope, so he became known as Dhan-Nis'ah (the one with the rope).