Sahih
حَدَّثَنَا الْحَسَنُ بْنُ عَلِيٍّ، حَدَّثَنَا ابْنُ نُمَيْرٍ، عَنْ عُبَيْدِ اللَّهِ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ إِذَا خَرَجَ يَوْمَ الْعِيدِ أَمَرَ بِالْحَرْبَةِ فَتُوضَعَ بَيْنَ يَدَيْهِ فَيُصَلِّي إِلَيْهَا وَالنَّاسُ وَرَاءَهُ وَكَانَ يَفْعَلُ ذَلِكَ فِي السَّفَرِ فَمِنْ ثَمَّ اتَّخَذَهَا الأُمَرَاءُ .
Ibn 'Umar said:When the Messenger of Allah (ﷺ) would go out (for prayer) on the day of 'Id, he ordered to bring a lance, it was then setup in front of him and he would pray in its direction, and the people (stood) behind him. He used to do so during journey ; hence the rulers would take it (lance with them)