It is narrated from Sayyiduna Wa'il bin Hujr (may Allah be pleased with him); he said: I was with the Prophet (peace and blessings be upon him) when suddenly a man entered leading another man by a rope, until he came to the Messenger of Allah (peace and blessings be upon him) and said: O Messenger of Allah, this man killed my brother. He (peace and blessings be upon him) said: "Did you kill him?" He said: Yes. He (peace and blessings be upon him) said: "How did you kill him?" He said: We were cutting firewood from a tree when he insulted me, so I struck him on the head with an axe and killed him. He (peace and blessings be upon him) said: "Do you have wealth with which to pay the blood money on your own behalf?" He said: No, by Allah, I have no wealth except my axe and my cloak. He (peace and blessings be upon him) said: "Do you think your people will pay the blood money on your behalf?" He said: I am of far less worth to my people than that. So he (peace and blessings be upon him) threw his rope to him (the brother) and said: "Take your man." When he turned to go, the Messenger of Allah (peace and blessings be upon him) said: "If he kills him, he will be like him." Then someone came to him and said: Woe to you! The Messenger of Allah (peace and blessings be upon him) is saying: "If he kills him, he will be like him." He said: O Messenger of Allah, I only took him by your command. He (peace and blessings be upon him) said: "Do you not want him to return bearing his own sin and the sin of your companion?" He said: Certainly, O Messenger of Allah. He (peace and blessings be upon him) said: "Then that is how it is." So he threw down his rope and said: "Go wherever you wish."
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18243