He was mounted on a horse the day the Muslims met the enemy in battle. The commander of the Muslims that day was Khalid bin Walid, whom Abu Bakr had dispatched. The enemy seized the horse, but when they were defeated, Khalid returned the horse to him.
أنه كان على فرس يوم لقي المسلمون- وأمير المسلمين يومئذ خالد بن الوليد بعثه أبو بكر- فأخذه العدو، فلما هزم العدو رد خالد فرسه.
Bukhari related it in the Book of Jihad and Expeditions (3069) from Ahmad bin Yunus, who said, Zuhayr narrated to us, from Musa bin Uqba, from Nafi, from Ibn Umar, who mentioned it.