Narrated Ibn `Abbas: Once I came riding a she-ass and had (just) attained the age of puberty. Allah's Messenger (ﷺ) was offering the prayer at Mina. There was no wall in front of him and I passed in front of some of the row while they were offering their prayers. There I let the she-ass loose to graze and entered the row, and nobody objected to it.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا إِسْمَاعِيلُ بْنُ أَبِي أُوَيْسٍ، قَالَ حَدَّثَنِي مَالِكٌ، عَنِ ابْنِ شِهَابٍ، عَنْ عُبَيْدِ اللَّهِ بْنِ عَبْدِ اللَّهِ بْنِ عُتْبَةَ، عَنْ عَبْدِ اللَّهِ بْنِ عَبَّاسٍ، قَالَ أَقْبَلْتُ رَاكِبًا عَلَى حِمَارٍ أَتَانٍ، وَأَنَا يَوْمَئِذٍ قَدْ نَاهَزْتُ الاِحْتِلاَمَ، وَرَسُولُ اللَّهِ صلى الله عليه وسلم يُصَلِّي بِمِنًى إِلَى غَيْرِ جِدَارٍ، فَمَرَرْتُ بَيْنَ يَدَىْ بَعْضِ الصَّفِّ وَأَرْسَلْتُ الأَتَانَ تَرْتَعُ، فَدَخَلْتُ فِي الصَّفِّ، فَلَمْ يُنْكَرْ ذَلِكَ عَلَىَّ.
sunnah.com