Musannaf Ibn Abi Shayba 27:600

Abu Usama narrated to us, he said: Al-A'mash narrated to us, from 'Amr ibn Murrah, from Abu al-Bakhtari, from 'Ali. They said: "Inform us about 'Abdullah." He said: "He learned the Qur'an and the Sunnah, then he stopped, and that is sufficient as knowledge."