عَنِ ابْنِ عُمَرَ قَالَ: كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَغْدُو إِلَى الْمُصَلَّى وَالْعَنَزَةُ بَيْنَ يَدَيْهِ تُحْمَلُ وَتُنْصَبُ بِالْمُصَلَّى بَيْنَ يَدَيْهِ فَيصَلي إِلَيْهَا. رَوَاهُ البُخَارِيّ
Translation

Ibn ‘Abbas said, “When I was near the age of puberty I came riding on a she-ass and found God’s Messenger leading the people in prayer at Mina with no wall in front of him. I passed in front of part of the row of worshippers, and dismounting, let my she-ass go to pasture and joined the row, and no one objected to that.” (Bukhari and Muslim.)