The Messenger of Allah ﷺ said, ” Goodness will remain in the forelocks of horses until the Day of Resurrection.” (Al-Bukhari and Muslim)

عن ابن عمر رضي الله عنهما أن رسول الله صلى الله عليه وسلم قال‏:‏ ‏ “‏الخيل معقود في نواصيها الخير إلى يوم القيامة‏”‏ ‏)‏متفق عليه(‏

The Prophet ﷺ also taught that, for example, one should not cut off the forelock of a horse because doing so would hurt the horse in its beauty experience. It is also prohibited to condescend or mock animals.

And he ﷺ said: “There is a blessing in the manes of the horses.” (Ahmad)

Utbah ibn Farqad Abu Abdillah al-Sulami related that the Messenger of God ﷺ said: “Do not cut the forehead tresses of horses, nor their tails, for with their tails they scare away the flies, the manes provide warmth and blessings are intertwined with the hair on their foreheads.” In another version: “Do not cut the forehead lure of a horse, for character speaks from his forehead lobe, nor his mane, for they provide protection, nor his tail, for he chases away the flies with it (both reported in the work of Abu Dawud ).

Anas bin Malik related that the Messenger of God ﷺ said, “There are blessings in the forehead locks of horses.” (Muslim)

The Prophet ﷺ said: ‘A horse can be kept for one of three purposes: for a man it can be a source of reward; for another it can be a means of life; and for a third it can be a burden (a source of sin).
As for the one for whom it is a source of reward, he is the one who keeps his horse for the sake of jihad in the cause of Allah; he ties it with a long rope to a meadow or in a garden. So whatever the rope allows it to eat, it will be considered good deeds that will be rewarded (to the owner). And if it breaks its rope and jumps over one or two hills, even its dung will be counted among its good deeds. If it passes through a river and drinks water from it, which will be considered good deeds for his benefit (the owner), even if he did not intend to water it.

A horse is a shelter for the person who keeps it so that he can earn his money by honest living and considers it as a refuge to keep him from following illegal ways (to make money), and do not forget the rights of Allah (Zakat) and allow others to use it for the sake of Allah.
But a horse is a burden, and a source of sin, for him who takes it out of pride and pretense and for the purpose of harming the Muslims. ”

The Prophet ﷺ was asked about donkeys. He replied: “Nothing has been revealed concerning them except this expanded verse (which includes everything): Then whoever has done good equal to the weight of an atom (or a small ant) will see it (his reward). And whoever has done evil equal to the weight of an atom (or a small ant) will see it (his punishment). (99.7-8)
(Sahih al-Bukhari 3646: Book 61, Hadith 149, Vol. 4, Book 56, Hadith 839)

Mu’äwiyah ibn Khadéj said that he once passed Abu Dharr al-Ghifari and he was standing near one of his horses, so Mu’äwiyah asked him why he was so concerned about his horse. Abu Dharr replied, “I think this horse’s duā has been heard.” Mu’äwiyah asked him, “And then what is the duā of an animal among the animals?” Abu Dharr said, “I swear by Those in which hands my life is, every horse performs a duā every morning saying,” O Allah! You have placed me in the care of a servant of Your servants, and You have placed my Rizk (sustenance) in his hands, so make me more dear to him than his family, wealth and children.” (Authentic Tradition Ahmad 5/162)
Abu Dharr al-Ghifari based this statement on a hadith of the Prophet ﷺ in which he said: “Every horse is allowed to perform two supplications every dawn The horse says, “O Allaah! You have brought me into the care of one of the children of Adam (‘alayhi sallam), so make me more beloved by him than his family and prosperity” or “…make me among the dearest of his wealth and household to him” (Recorded by Ahmad, al-Nasa’I , al-Hakim and in saheeh al-Jami # 2414 and mentioned in Tafsir ibn Kathir)

A man once came to the Prophet ﷺ and said: “O Messenger of Allah! Are there horses in Paradise, because I love horses?” The Prophet ﷺ replied: “If Allah allows you to enter Paradise and you will wish to mount a winged horse of red ruby flying in Paradise wherever you wish, then you will certainly accomplish this.”

Then the Bedouin asked: “O Messenger of Allah! Are there camels in Paradise?” The Prophet ﷺ replied: “O Bedouin! If Allah allows you to enter Paradise, then you will certainly get what your soul desires and what your eye desires in it!” (Sahih at-Targhieb wat-Tarhieb: 3756)

Abdullaah ibn ‘Amr said, “In Paradise there are young horses and swift, powerful mounts that will be ridden by the people of Paradise.”

A man asked al-Hasan al-Basrie, “Are there any horses in Paradise?” He replied, “There is in it that which the souls desire and the eyes desire.”