Musnad Ahmad 27:1238

'Abd al-Samad narrated to us, 'Abd al-'Aziz—meaning Ibn Muslim—narrated to us, 'Abd Allah—meaning Ibn Dinar—narrated to us, from Ibn 'Umar, that when he would depart from the Friday [prayer], he would depart to his house, and he would prostrate two prostrations. And he mentioned, "That the Messenger of Allah, peace and blessings of Allah be upon him, used to do that."