Musannaf Ibn Abi Shayba 17:1137

Abu Usama narrated to us, from Shu'bah, from Jabir, from Abdullah ibn Yasar, who said: I heard Ali delivering a sermon, saying: "I adjure anyone who has a book to return and erase it. For the people are only like this: they follow the narrations of their scholars and have abandoned the Book of their Lord."