Hadith 9:6
Sahih (Darussalam)
Narrated Ibn Umar:
It was narrated from Ibn Umar concerning the Messenger of Allah (ﷺ) he said: "He used to set up a short spear then pray facing toward it."
أَخْبَرَنَا عُبَيْدُ اللَّهِ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا يَحْيَى، عَنْ عُبَيْدِ اللَّهِ، قَالَ أَنْبَأَنَا نَافِعٌ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ كَانَ يَرْكُزُ الْحَرْبَةَ ثُمَّ يُصَلِّي إِلَيْهَا
Original Reference: Sunan an-Nasa'i 747