Musannaf Ibn Abi Shayba 3:928

Shababa narrated to us, he said: Layth ibn Sa'd narrated to us, from Ibn Shihab, from Anas, that the Prophet (peace and blessings of Allah be upon him) used to pray the Asr prayer while the sun was high and bright. So the person departing would go and arrive at the Al-Awali (the high lands of Medina) while the sun was still high.