Sahih Muslim
The Book Pertaining to the Oath, for Establishing the Responsibility of Murders, Fighting, Requital and Blood-Wit (Kitab Al-Kitab Al-Qasama wal-Muharaba wal-Qisas wal-Diyat)
Book Number: 016 / Hadith Number: 4158
'Abdullah b. (Mas'ud) reported Allah's Messenger (may peace be upon him) as saying: The first (thing) that will be decided among people on the Day of Judgment will pertain to bloodshed.