سنن النسائي

It was narrated from Yahya, from Bushair bin Yasa, from Sahl bin Abi Hathmah who said - and I think he said: and from Rafi bin Khadij, the two of them said - :"Abdullah bin Sahl bin Zaid and Muhayysah bin Mas'ud went out until when they reached Khaibar, they went their separate ways. Then Muhayysah found 'Abdullah bin Sahl slain, so he buried him. Then he came to the Mesenger of Allah, along with Huwayysah bin Mas'ud and 'Abdur-Rahman bin Sahl, who was the youngest of them, 'Abdur-Rahman started to speak before his two companions, but the Messenger of Allah (ﷺ) said to him: "Let the clear speak first." So he fell silent and his two companions spoke, then he spoke with them. They told the Messenger of Allah (ﷺ) about the killing of 'Abdullah bin Sahl, and he said to them: "Will you swear fifty oaths, then you will receive compensation, or be entitled to retaliate?" They said: "How can we swear an oath when we did not witness what happened?" he said: "Then can the Jews swear fifty oaths declaring their innocence?" They said: "How can we accept the oath of a disbelieving people?" When the Messenger of Allah (ﷺ) saw that, he paid the blood money (himself).