Musnad Abu Ya'la al-Mawsili 166:17

Isma'il ibn Yusuf al-Basri narrated to us, 'Umar ibn Harun al-Balkhi narrated to us, from Sufyan, from 'Abdullah ibn 'Abdullah ibn Ja'far, from his father, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "If you see someone who is ascetic regarding the worldly life, then draw near to him, for he casts wisdom."