The Book Pertaining to the Oath, for Establishing the Responsibility of Murders, Fighting, Requital and Blood-Wit (Kitab Al-Kitab Al-Qasama wa'l-Muharaba wa'l-Qisas wa'l-Diyat)
Muslim :: Book 16 : Hadith 4127
Sulaiman b. Yasar, the freed slave of Maimuna, the wife of Allah's Apostle (may peace be upon him), narrated from one of the Ansari Companions of Allah's Messenger (may peace be upon him) that Allah's Messenger (may peace be upon him) retained (the practice) of Qasama as it was in the pre-Islamic days.