Musannaf Ibn Abi Shayba 3:921

Jarir ibn Abd al-Hamid narrated to us, from Mansur, from Rib'i ibn Hirash, from Abu al-Abyad, from Anas, who said: The Messenger of Allah (peace be upon him) used to pray the Asr prayer while the sun was white and high. Then I would go to my clan on the side of Medina, and they would not have prayed yet. So I would say, "What is detaining you? Pray, for the Messenger of Allah (peace be upon him) has already prayed."