One-fifth of Booty to the Cause of Allah (Khumus)

Bukhari :: Book 4 :: Volume 53 :: Hadith 362

Narrated Nafi from Ibn Umar:

Allah's Apostle 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.