Musannaf Ibn Abi Shayba 37:345

'Affan narrated to us, he said: Sulaym ibn Akhdar narrated to us, he said: Ibn 'Awn narrated to us, he said: Muslim ibn Yasar was of higher status among the people of Basra than al-Hasan, until he went out with Ibn al-Ash'ath, while al-Hasan refrained. Abu Sa'id did not cease to be in a state of loftiness after that, while the other fell.