Musannaf Ibn Abi Shayba 28:828

Ali ibn Mushir narrated to us, from Ubayd Allah, from Nafi, from Ibn Umar, that a slave of his ran away and took a horse of his with him, and he entered the land of the enemy. Khalid ibn al-Walid overcame him and returned one of them to him during the lifetime of the Messenger of Allah (may Allah bless him and grant him peace), and he returned the other after the death of the Messenger of Allah (may Allah bless him and grant him peace).