(8) باب التَّطَوُّعِ عَلَى الرَّاحِلَةِ وَالْوِتْرِ
Narrated Anas ibn Malik:
When the Messenger of Allah (ﷺ) was on a journey and wished to say voluntary prayer, he made his she-camel face the qiblah and uttered the takbir (Allah is most great), then prayed in whatever direction his mount made his face.
Reference: Sunan Abi Dawud 1225
In-book reference: Book 4, Hadith 28
English translation: Book 4, Hadith 1221