Bulugh al-Maram:Jihad:Hadith 1482
وَلِأَبِي دَاوُدَ: { أَسْهَمَ لِرَجُلٍ وَلِفَرَسِهِ ثَلَاثَةَ أَسْهُمٍ: سَهْمَيْنِ لِفَرَسِهِ, وَسَهْماً لَهُ } 1‏ .‏‏1 ‏- صحيح.‏ رواه أبو داود ( 2733 )‏.‏

Abu Dawud also reported, ‘He allotted three shares for a man and his horse, two for his horse and one for him.’