Musnad Abu Ya'la al-Mawsili 118:69

Ishaq narrated to us, Abd al-Razzaq narrated to us, Ma'mar informed us, from al-Zuhri, from Anas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) would pray the Asr prayer, then the one going to the al-Awali (outskirts of Medina) would depart while the sun was still high.