Sahih al-Bukhari 2852Book 56, Hadith 68
حَدَّثَنَا أَبُو نُعَيْمٍ، حَدَّثَنَا زَكَرِيَّاءُ، عَنْ عَامِرٍ، حَدَّثَنَا عُرْوَةُ الْبَارِقِيُّ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " الْخَيْلُ مَعْقُودٌ فِي نَوَاصِيهَا الْخَيْرُ إِلَى يَوْمِ الْقِيَامَةِ الأَجْرُ وَالْمَغْنَمُ ".
The Prophet (ﷺ) said, "Good will remain (as a permanent quality) in the foreheads of horses (for Jihad) till the Day of Resurrection, for they bring about either a reward (in the Hereafter) or (war) booty (in this world)."