Mishkat al-Masabih
Abu Huraira reported God’s Messenger as saying, "If anyone reserves a horse in God’s path with faith in God and belief in His promise, its food, drink, dung and urine will be in his scale on the day of resurrection.” Bukhari transmitted it.
وَعَنْ أَبِي هُرَيْرَةَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «مَنِ احْتَبَسَ فَرَسًا فِي سَبِيل الله إِيمَانًا وتصْديقاً بوَعْدِه فإِنَّ شِبَعَه ورِيَّه ورَوْثَه وبَوْلَه فِي مِيزَانه يَوْم الْقِيَامَة» . رَوَاهُ البُخَارِيّ
Reference