English Translation
Narrated Nafi: Once a slave of Ibn 'Umar fled and joined the Byzantine. Khalid bin Al-Walid got him back and returned him to 'Abdullah (bin 'Umar). Once a horse of Ibn 'Umar also ran away and followed the Byzantines, and he (i.e. Khalid) got it back and returned it to 'Abdullah.
This hadith is from Sahih al-Bukhari, the most rigorously authenticated collection in Islamic scholarship. No editorial opinion is added.