Sunan An-Nasa'i

Alqamah bin Wa'il narrated from his father that he was sitting with the Messenger of Allah when a man came leading another man by a string. He said:""O Messenger of Allah, this man killed my brother."" The Messenger of Allah said to him: ""Did you kill him?"" He said: ""O Messenger of Allah even if he did not confess I would have brought proof against him."" He said: ""Yes, I killed him."" He said: ""How did you kill him?"" He said: ""He and I were chopping firewood from a tree and he insulted me, so I got angry and struck him with the ax on the forehead."" The Messenger of Allah said: ""Do you have any wealth with which you can pay the Diyah to save yourself?"" He said: ""O Messenger of Allah, I do not have anything but my ax and my clothes."" The Messenger of Allah said to him: ""Do you think your people will pay to save you?"" He said: ""I am too insignificant to them for that."" He threw the string to the man and said: ""Here, thank him."" When he turned to go, the Messenger of Allah said: ""If he kills him, he will be like him. ""They caught up with the man, and said: ""Woe to you! The Messenger of Allah said: 'If he kills him, he will be like him. ""So he went back to the Messenger of Allah and said: ""O Messenger of Allah, I have been told that you said: 'if he kills him, he will be like him. 'But I only took him because you told me to. He said: 'Don't you want him to carry your sin and the sin of your companion (the victim)?' He said: 'Yes, if that is the case.' He said: 'And that is how it is