Musnad Abu Ya'la al-Mawsili 151:9

Abu Bakr ibn Abi Shaybah narrated to us, Hafs narrated to us, from al-A'mash, from Abu Ishaq, from Abu al-Ahwas, from Abdullah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, Islam began as something strange, and it will return as it began, so glad tidings to the strangers." It was said: "And who are the strangers?" He said: "Those who detach themselves from the tribes."