Musnad Abu Ya'la al-Mawsili 118:70

Zuhayr narrated to us, Ubayd Allah ibn Abd al-Majid al-Hanafi narrated to us, Ibn Abi Dhi'b narrated to us, from Ibn Shihab, from Anas: That the Messenger of Allah (peace be upon him) used to pray the Asr prayer while the sun was white and vivid. Then the person going to the Al-Awali (outskirts of Medina) would depart, and he would reach them while the sun was still high.