The Messenger of Allah ﷺ used to pray witr on his mount.  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يُوتِرُ عَلَى الرَّاحِلَةِ  

Ibn Umar used to pray witr on his camel and he mentioned that the Prophet ﷺ used to do that.  

أَنَّ النَّبِيَّ ﷺ كَانَ يَفْعَلُ ذَلِكَ  

"Ibn Umar said to me that the Messenger of Allah ﷺ used to pray witr on a camel."  

أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يُوتِرُ عَلَى الْبَعِيرِ