Hadith 700
حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ نُمَيْرٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا عُبَيْدُ اللَّهِ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يُصَلِّي سُبْحَتَهُ حَيْثُمَا تَوَجَّهَتْ بِهِ نَاقَتُهُ .
Ibn 'Umar reported that the Messenger of Allah (ﷺ) used to say Nafl prayer on (the back of) his camel in whatever direction it took him.
Reference : Sahih Muslim 700a
In-book reference : Book 6, Hadith 41
USC-MSA web (English) reference : Book 4, Hadith 1497