Hadith: Goodness is tied to the forelocks of horses until the Day of Resurrection

عن ابن عمر رضي الله عنهما : أن رسول الله صلى الله عليه وسلم قال: «الخَيْل مَعقُودٌ في نَوَاصِيهَا الخَيْر إلى يوم القِيامة». وعن عروة البارقي رضي الله عنه : أن النبي صلى الله عليه وسلم قال: «الخيل مَعقُودٌ في نَوَاصِيهَا الخَيْر إلى يوم القيامة: الأجر، والمَغْنَم».
[صحيح] - [حديث ابن عمر متفق عليه. وهذا لفظ البخاري. حديث عروة البارقي متفق عليه]

‘Abdullāh ibn ‘Umar (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said: "Goodness is attached to the forelocks of horses until the Day of Resurrection." ‘Urwah al-Bāriqi (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Goodness is attached to the forelocks of horses until the Day of Resurrection: (in terms of) reward and spoils of war."
Sahih/Authentic. - [Al-Bukhari and Muslim with its two versions]

Explanation

Horses are a source of goodness for the believer until the Day of Resurrection. There is a reward for preparing steeds of war to fight in the cause of Allah, and this a deferred reward that will be realized in the Hereafter. And there is an immediate reward which is the spoils of war that the warrior earns from the possessions of the enemy.