Musnad Abu Ya'la al-Mawsili 42:220

Narrated to us Zuhayr, narrated to us Abd al-Rahman ibn Mahdi, narrated to us Mahdi ibn Maymun, from Muhammad ibn Sirin, from Ma'bad ibn Sirin, from Abu Sa'id al-Khudri, from the Prophet (may Allah bless him and grant him peace), who said: "People will emerge from the direction of the East who recite the Quran, but it will not pass beyond their collarbones. They will pass through the religion just as an arrow passes through the game, and they will not return to it until the arrow returns to its notch. Their mark is shaving and shortening."