Hadith 465
حضرت الصلاة صلاة المكتوبة ونحن مع رسول الله صلى الله عليه وسلم على ركابنا فتقدم بنا ثم امنا فصلينا على ركابنا
"The time for the obligatory prayer arrived while we were with the Messenger of Allah (peace and blessings be upon him) on our mounts. So he (peace and blessings be upon him) moved forward and led us in prayer, and we performed the prayer on our mounts."