One-fifth of Booty to the Cause of Allah (Khumus)
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، أَخْبَرَنَا مَالِكٌ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم بَعَثَ سَرِيَّةً فِيهَا عَبْدُ اللَّهِ قِبَلَ نَجْدٍ، فَغَنِمُوا إِبِلاً كَثِيرًا، فَكَانَتْ سِهَامُهُمُ اثْنَىْ عَشَرَ بَعِيرًا أَوْ أَحَدَ عَشَرَ بَعِيرًا، وَنُفِّلُوا بَعِيرًا بَعِيرًا.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
From Sahih al-Bukhari, whose reports the scholars accept as authentic.