Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
bukhari:1000Mūsá b. Ismāʿīl > Jūwayriyah b. Asmāʾ > Nāfiʿ > Ibn ʿUmar

The Prophet ﷺ used to offer (Nawafil) prayers on his Rahila (mount) facing its direction by signals, but not the compulsory prayer. He also used to pray witr on his (mount) Rahila.  

البخاري:١٠٠٠حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ قَالَ حَدَّثَنَا جُوَيْرِيَةُ بْنُ أَسْمَاءَ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ قَالَ

كَانَ النَّبِيُّ ﷺ يُصَلِّي فِي السَّفَرِ عَلَى رَاحِلَتِهِ حَيْثُ تَوَجَّهَتْ بِهِ يُومِئُ إِيمَاءً صَلاَةَ اللَّيْلِ إِلاَّ الْفَرَائِضَ وَيُوتِرُ عَلَى رَاحِلَتِهِ