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

Bukhari :: Book 4 :: Volume 53 :: Hadith 389

Narrated Yahya bin Said:

Once the Prophet called the Ansar in order to grant them part of the land of Bahrain. On that they said, "No! By Allah, we will not accept it unless you grant a similar thing to our Quarries brothers as well." He said, "That will be their's if Allah wishes." But when the Ansar persisted in their request, he said, "After me you will see others given preference over you in this respect (in which case) you should be patient till you meet me at the Tank (of Al-Kauthar)."