Bukhari

Hadith Commentary:

The intended meaning is the spoils of war (mal-e-ghanīmah) which used to be obtained by the mounted mujahideen as a result of victory. Even today, the horse holds great importance for military needs.

Hadith Commentary:
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By "nawasi al-khayl" are meant those hairs that hang on the horse’s forehead.
The intent here is not merely the hair, but it is a figure of speech referring to the entire being, i.e., the whole horse is a bearer of goodness and blessing.
➋
The aforementioned prophecy of the Messenger of Allah (sallallahu alayhi wa sallam) was fulfilled word for word.
Even today, the importance of the horse in the army is undeniable.
It is kept for military needs, and in fact, a dedicated department regarding it is established within the army.
High-quality horses are imported for this purpose, and soldiers are trained to ride them.
The need for horses will remain until the Day of Judgment.
Their goodness and blessing lie in the fact that their necessity will persist, no matter how modern the era becomes.

Hadith Commentary:
By "al-khayl" (the horses) is meant those horses that are kept for the purpose of jihad.
In such horses, there is indeed great goodness and blessing.
Even in this world, Allah Ta'ala will bestow His grace and bounty upon the one who takes care of these horses, and on the Day of Resurrection, even their dung and urine will be placed in his record of deeds.
And their weight will be measured and good deeds will be given accordingly.
In any case, the horse holds a prominent status among riding animals and, in terms of loyalty, is a beloved animal for humans—especially in the battlefield, riding a horse holds great importance.
Even today, in the modern era when the best means of transportation have been invented, the importance of the horse remains undisputed.
There is no government in the world whose army does not have a cavalry unit.

Urdu marginal note:
By these horses are meant the horses used in warfare. For details regarding the blessing, see Hadith: 3591.