كتاب الصلاة
2  
The Book of Prayer
Bulugh al-Maram 213
Narrated 'Aamir bin Rabi'ah (RA):
I saw Allah's Messenger (ﷺ) praying while mounted on his riding animal facing whatever direction it faced. [Agreed upon].
وَعَنْ عَامِرِ بْنِ رَبِيعَةَ ‏- رضى الله عنه ‏- قَالَ : { رَأَيْتُ رَسُولَ اَللَّهِ ‏- صلى الله عليه وسلم ‏-يُصَلِّي عَلَى رَاحِلَتِهِ حَيْثُ تَوَجَّهَتْ بِهِ } مُتَّفَقٌ عَلَيْهِ .‏ 1
Reference : Bulugh al-Maram 213
In-book reference : Book 2, Hadith 213
English translation : Book 2, Hadith 211
Bulugh al-Maram 213
al-Bukhari added:
"Making gestures with his head and he did not do that (pray while mounted) with obligatory prayers."
زَادَ اَلْبُخَارِيُّ : { يُومِئُ بِرَأْسِهِ , وَلَمْ يَكُنْ يَصْنَعُهُ فِي اَلْمَكْتُوبَةِ } 1‏ .‏
Reference : Bulugh al-Maram 213
In-book reference : Book 2, Hadith 213
Hadith Text
Reference