حَدَّثَنَا أَحْمَدُ بْنُ صَالِحٍ، حَدَّثَنَا ابْنُ وَهْبٍ، أَخْبَرَنِي يُونُسُ، عَنِ ابْنِ شِهَابٍ، عَنْ سَالِمٍ، عَنْ أَبِيهِ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُسَبِّحُ عَلَى الرَّاحِلَةِ أَىَّ وَجْهٍ تَوَجَّهَ وَيُوتِرُ عَلَيْهَا غَيْرَ أَنَّهُ لاَ يُصَلِّي الْمَكْتُوبَةَ عَلَيْهَا ‏.‏
Translation
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.