Musannaf Ibn Abi Shayba 3:2989

Abu Bakr narrated to us, he said: Sufyan ibn 'Uyaynah narrated to us, from 'Amr, from al-Zuhri, from Salim, from Ibn 'Umar, that the Prophet, peace and blessings of Allah be upon him, used to pray two rak'ahs after the Friday prayer.