Sunan Ibn Majah, Chapter: The Chapters on Jihad

said that a horse of his went out and the enemy captured it. Then the Muslims defeated them and it was returned to him. (That was) during the time of the Messenger of Allah (saw). He said: "And a slave of his absconded and joined up with the Romans, then the Muslims defeated them, and Khalid bin Walid returned him to me, after the death of the Messenger of Allah (saw)."