The Messenger of Allah ﷺ used to plant a spear in the ground and pray facing it.
حدثنا يحيى عن عبيد الله حدثني نافع
كان رسول الله ﷺ يركز الحربة يصلي إليها
Its isnad is sahih, and it is an abridgment of a hadith agreed upon [by Bukhari and Muslim], found in al-Muntaqa 1131.