Narrated ʿAbdullah bin Amir that his father had told him that he had seen the Prophet ﷺ praying Nawafil at night on the back of his Mount on a journey, facing whatever direction it took. (Using translation from Bukhārī 1104)
أَخْبَرَهُ أَنَّهُ رَأَى رَسُولَ اللهِ ﷺ يُصَلِّي فِي السُّبْحَةِ بِاللَّيْلِ فِي السَّفَرِ عَلَى ظَهْرِ رَاحِلَتِهِ حَيْثُ تَوَجَّهَتْ بِهِ