Sahih al-Bukhari, Hadith 2853 ⓘ
Narrated Abu Huraira: The Prophet said, "If somebody keeps a horse in Allah's Cause motivated by his faith in Allah and his belief in His Promise, then he will be rewarded on the Day of Resurrection for what the horse has eaten or drunk and for its dung and urine."
حَدَّثَنَا عَلِيُّ بْنُ حَفْصٍ، حَدَّثَنَا ابْنُ الْمُبَارَكِ، أَخْبَرَنَا طَلْحَةُ بْنُ أَبِي سَعِيدٍ، قَالَ سَمِعْتُ سَعِيدًا الْمَقْبُرِيَّ، يُحَدِّثُ أَنَّهُ سَمِعَ أَبَا هُرَيْرَةَ ـ رضى الله عنه ـ يَقُولُ قَالَ النَّبِيُّ صلى الله عليه وسلم " مَنِ احْتَبَسَ فَرَسًا فِي سَبِيلِ اللَّهِ إِيمَانًا بِاللَّهِ وَتَصْدِيقًا بِوَعْدِهِ، فَإِنَّ شِبَعَهُ وَرِيَّهُ وَرَوْثَهُ وَبَوْلَهُ فِي مِيزَانِهِ يَوْمَ الْقِيَامَةِ " .
also referenced under: Book 56, Hadith 69 (In-Book) & Volume 4, Book 52, Hadith 105 (USC-MSA)