Sayyiduna ‘Amir (may Allah be pleased with him) narrates: I saw the Messenger of Allah (peace and blessings be upon him) praying on his mount, whichever direction it was facing.
Hadith Referenceصحيح ابن خزيمه / جماع أبواب صلاة التطوع فى السفر على الدواب / 1265