Musnad Ahmad 30:1452

'Affan narrated to us, Hammam narrated to us, Qatadah narrated to us, from Abu Ayyub al-'Ataki—and he is Yahya ibn Malik—and 'Affan said once: He said: Abu Ayyub narrated to us, from Abu Hurairah, who said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "If one of you fights, let him avoid the face."