Qatadah said: When Sayyiduna Anas bin Malik (may Allah be pleased with him) passed away, Muwarriq al-Ijli said: "Today half of knowledge has gone." It was asked: O Abu al-Mu'tamir, how is that? He said: "When a man from the people of innovation differed with us about a hadith of the Messenger of Allah (peace and blessings be upon him), we would say to him: Come to the one who heard it from him (peace and blessings be upon him) himself."
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 715