Nafi' narrates from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that a slave of his joined the enemy on a horse of his. Sayyiduna Khalid bin al-Walid (may Allah be pleased with him) seized them both and returned them to him.
This is how Abu Mu'awiyah narrated it, while Abdullah bin Numayr, from Ubaydullah, made clear which of this happened in the time of the Prophet (peace and blessings be upon him) and which happened after him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18247