Musnad Abu Ya'la al-Mawsili 129:99

Abu Bakr ibn Abi Shaybah narrated to us, al-Thaqafi narrated to us, from Humayd, from Anas, that the Prophet (may Allah bless him and grant him peace) used to like for the Emigrants (Muhajirun) and the Helpers (Ansar) to be next to him, so that they could take [knowledge] from him.