Musannaf Ibn Abi Shayba 33:1095

'Affan narrated to us, he said: Abu 'Aqil Bashir bin 'Uqbah narrated to us, he said: I heard al-Hasan saying: The scholars are three: among them is a scholar for himself and for others, and that is the best of them and the most excellent of them. And among them is a scholar for himself, and that is good. And among them is a scholar neither for himself nor for others, and that is the worst of them.