Bulugh al-Maram, Book 11, Hadith 1330 (English)

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

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

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also referenced under: Book 11, Hadith 1303 (In-Book)