Abu Dawud Book 34, Hadith Number 4508.
Narated By N/A : Bashir b. Yasir told that a man of the Ansar called Sahl b. Abu Hathmah told him that some people of his tribe went to Khaibar and separated there. They found one of them slain. They said to those with whom they had found him: You have killed our friend. They replied: We did not kill him, nor do we know the slayer. We (the people of the slain) then went to the Prophet of Allah (may peace be upon him). He said to them: Bring a proof against the one who has slain him. They replied: We have no proof. He said: Then they will take an oath for you. They said: We do not accept the oaths of the Jewr. The Apostle of Allah (may peace be’ upon him) did not like that no responsibility should be fixed for his blood. So he himself paid his bloodwit consisting of one hundred camels of sadaqah (i.e. camels sent to the Prophet as zakat).