"The Messenger of Allah ﷺ divided the spoils as two shares for the horse and one share for the man."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَسَمَ فِي النَّفَلِ لِلْفَرَسِ بِسَهْمَيْنِ وَلِلرَّجُلِ بِسَهْمٍ  

Another chain with similar meaning. There are narrations on this topic from Mujammi' bin Jariyah, Ibn 'Abbas, and Ibn Abi 'Amrah from his father. This Hadith of Ibn 'Umar is a Hasan Sahih Hadith. This is acted upon according to most of the people of knowledge among the Companions of the Prophet ﷺ and others. This is the view of Sufyan At-Thawri, Al-Awzai', Malik bin Anas, Ibn Al-Mubarak, Ash-Shafi'i, Ahmad and Ishaq. They said that the horsemen gets three shares, one share is for him and two shares for his horse. The foot soldiers get one share.  

عَنْ أَبِيهِ وَهَذَا حَدِيثُ ابْنِ عُمَرَ حَدِيثٌ حَسَنٌ صَحِيحٌ وَالْعَمَلُ عَلَى هَذَا عِنْدَ أَكْثَرِ أَهْلِ الْعِلْمِ مِنْ أَصْحَابِ النَّبِيِّ ﷺ وَغَيْرِهِمْ وَهُوَ قَوْلُ سُفْيَانَ الثَّوْرِيِّ وَالأَوْزَاعِيِّ وَمَالِكِ بْنِ أَنَسٍ وَابْنِ الْمُبَارَكِ وَالشَّافِعِيِّ وَأَحْمَدَ وَإِسْحَاقَ قَالُوا لِلْفَارِسِ ثَلاَثَةُ أَسْهُمٍ سَهْمٌ لَهُ وَسَهْمَانِ لِفَرَسِهِ وَلِلرَّاجِلِ سَهْمٌ