The Prophet ﷺ used to pray (the Nawafil) on his Mount facing east and whenever he wanted to offer the compulsory prayer, he used to dismount and face the Qibla. (Using translation from Bukhārī 1099)
«أَنَّ رَسُولَ اللَّهِ ﷺ كَانَ يُصَلِّي عَلَى رَاحِلَتِهِ نَحْوَ الْمَشْرِقِ فَإِذَا أَرَادَ أَنْ يُصَلِّيَ الْمَكْتُوبَةَ نَزَلَ فَاسْتَقْبَلَ الْقِبْلَةَ»