Musannaf Ibn Abi Shayba 3:475

Waki’ narrated to us, from Mis’ar, from al-Walid ibn Abi Malik, from Abu ‘Ubayd Allah, from Ibn ‘Umar, that the Messenger of Allah (may Allah bless him and grant him peace) used to have the spear planted for him on the day of Eid, and he would pray facing it.