Sayyiduna Rafi' bin Khadij (may Allah be pleased with him) says: A man of the Ansar was found killed at Khaybar. His relatives went to the Messenger of Allah (peace and blessings be upon him) and told him about it. He (peace and blessings be upon him) said: "Do you have two witnesses who can testify against the killer of your companion?" They said: O Messenger of Allah, no Muslim was present there; there were only Jews, and they dare to commit even greater crimes than this. He (peace and blessings be upon him) said: "Then choose fifty of them and make them swear an oath." Then the Messenger of Allah (peace and blessings be upon him) paid their blood money (diyah) from his own wealth.
Hadith Referenceالمعجم الكبير للطبراني / باب الراء / 4398