Sahih al-Bukhari — One-fifth of Booty to the Cause of Allah (Khumus) — Hadith No: 3134
Translation
Narrated Nafi` from Ibn `Umar:Allah's Messenger (ﷺ) sent a Sariya towards Najd, and `Abdullah bin `Umar was in the Sariya. They gained a great number of camels as war booty. The share of each one of them was twelve or eleven camels, and they were given an extra camel each