Musnad Abu Ya'la al-Mawsili 152:31

Abu al-Rabi' narrated to us, Abu Shihab narrated to us, from al-A'mash, from Abu Wa'il, from Abdullah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The first thing that will be judged between people on the Day of Resurrection is [regarding] the blood."