Sahih al-Bukhari 4228
Narrated Ibn `Umar:
On the day of Khaibar, Allah's Messenger (ﷺ) divided (the war booty of Khaibar) with the ratio of two shares 
for the horse and one-share for the foot soldier. (The sub-narrator, Nafi` explained this, saying, "If a 
man had a horse, he was given three shares and if he had no horse, then he was given one share.")
حَدَّثَنَا الْحَسَنُ بْنُ إِسْحَاقَ، حَدَّثَنَا مُحَمَّدُ بْنُ سَابِقٍ، حَدَّثَنَا زَائِدَةُ، عَنْ عُبَيْدِ اللَّهِ بْنِ عُمَرَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ ـ رضى الله عنهما ـ قَالَ قَسَمَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَوْمَ خَيْبَرَ لِلْفَرَسِ سَهْمَيْنِ، وَلِلرَّاجِلِ سَهْمًا‏.‏ قَالَ فَسَّرَهُ نَافِعٌ فَقَالَ إِذَا كَانَ مَعَ الرَّجُلِ فَرَسٌ فَلَهُ ثَلاَثَةُ أَسْهُمٍ، فَإِنْ لَمْ يَكُنْ لَهُ فَرَسٌ فَلَهُ سَهْمٌ‏.‏