Musnad Abu Ya'la al-Mawsili 42:372

Zuhayr narrated to us, Ishaq bin Yusuf narrated to us, 'Awf narrated to us, from Abu Nadrah, from Abu Sa'id al-Khudri, who said: The Messenger of Allah (ﷺ) said: "My Ummah will split into two factions, and a renegade group will emerge between them, which will be killed by the faction that is closer to the truth."