Musannaf Ibn Abi Shayba 3:3233

Abu Bakr narrated to us, he said: Ibn ‘Ulayyah narrated to us, from Ayyub, from Nafi’, who said: Ibn ‘Umar used to pray the morning prayer in the Mosque of the Messenger of Allah (may Allah bless him and grant him peace). Then he would go out, just as he was, to the prayer ground (musalla).