Chapter 45: The Book of Oaths (qasamah), Retaliation and Blood Money
it was narrated from Abu Salamah and Sulaiman bin Yasar, from some of the Companions of the Messenger of Allah, that: Qasamah existed during the Jahiliyyah and the Messenger of Allah approved of it as it had been during the Jahiliyyah, and he ruled accordingly among some of the Ansar concerning a victim whom they claimed the Jews of Khaibar had Killed. (Sahih)
Ma' mar contradicted the two of them.
Sunan an-Nasa'i 4708