(187) باب إِذَا غَنِمَ الْمُشْرِكُونَ مَالَ الْمُسْلِمِ ثُمَّ وَجَدَهُ الْمُسْلِمُ
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.
Reference: Sahih al-Bukhari 3068
In-book reference: Book 56, Hadith 274
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 52, Hadith 302