The Sutra of the Imam is also a Sutra for those who are behind him

Narrated Ibn 'Abbas:

Once I came riding a she-ass when I had just attained the age of puberty. Allah's Apostle was offering the prayer at Mina with no wall in front of him and I passed in front of some of the row. There I dismounted and let my she-ass loose to graze and entered the row and nobody objected to me about it.

حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، قَالَ أَخْبَرَنَا مَالِكٌ، عَنِ ابْنِ شِهَابٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ عُتْبَةَ، عَنْ عَبْدِ اللَّهِ بْنِ عَبَّاسٍ، أَنَّهُ قَالَ أَقْبَلْتُ رَاكِبًا عَلَى حِمَارٍ أَتَانٍ، وَأَنَا يَوْمَئِذٍ قَدْ نَاهَزْتُ الاِحْتِلاَمَ، وَرَسُولُ اللَّهِ ﷺ يُصَلِّي بِالنَّاسِ بِمِنًى إِلَى غَيْرِ جِدَارٍ، فَمَرَرْتُ بَيْنَ يَدَىْ بَعْضِ الصَّفِّ، فَنَزَلْتُ وَأَرْسَلْتُ الأَتَانَ تَرْتَعُ، وَدَخَلْتُ فِي الصَّفِّ، فَلَمْ يُنْكِرْ ذَلِكَ عَلَىَّ أَحَدٌ.

Narrated Ibn 'Umar:

Whenever Allah's Apostle came out on 'Id day, he used to order that a Harba (a short spear) to be planted in front of him (as a Sutra for his prayer) and then he used to pray facing it with the people behind him and used to do the same while on a journey. After the Prophet , this practice was adopted by the Muslim rulers (who followed his traditions).

حَدَّثَنَا إِسْحَاقُ، قَالَ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ نُمَيْرٍ، قَالَ حَدَّثَنَا عُبَيْدُ اللَّهِ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ إِذَا خَرَجَ يَوْمَ الْعِيدِ أَمَرَ بِالْحَرْبَةِ فَتُوضَعُ بَيْنَ يَدَيْهِ، فَيُصَلِّي إِلَيْهَا وَالنَّاسُ وَرَاءَهُ، وَكَانَ يَفْعَلُ ذَلِكَ فِي السَّفَرِ، فَمِنْ ثَمَّ اتَّخَذَهَا الأُمَرَاءُ.