(8) باب التَّطَوُّعِ عَلَى الرَّاحِلَةِ وَالْوِتْرِ
Narrated Ibn 'Umar:
While travelling the Messenger of Allah (ﷺ) would pray voluntary prayer on his riding beast in whatever direction it turned; and he would observe witr prayer, but he did not offer the obligatory prayers upon it.
Reference: Sunan Abi Dawud 1224
In-book reference: Book 4, Hadith 27
English translation: Book 4, Hadith 1220