وَالْخَيْلَ وَالْبِغَالَ وَالْحَمِيرَ لِتَرْكَبُوهَا وَزِينَةً وَيَخْلُقُ مَا لاَ تَعْلَمُونَ – النحل: 8
And [He created] the horses, mules and donkeys for you to ride and [as] adornment. And He creates that which you do not know. (Quran 16:8)
There are several other places in Quran where horse is mentioned such as:
Beautified for people is the love of that which they desire – of women and sons, heaped-up sums of gold and silver, fine branded horses, and cattle and tilled land. That is the enjoyment of worldly life, but Allah has with Him the best return. (Quran 3:14)
And incite [to senselessness] whoever you can among them with your voice and assault them with your horses and foot soldiers and become a partner in their wealth and their children and promise them.” But Satan does not promise them except delusion. (Quran 17:64)
[Mention] when there were exhibited before him in the afternoon the poised [standing] racehorses. (Quran 38:31)
And what Allah restored [of property] to His Messenger from them – you did not spur for it [in an expedition] any horses or camels, but Allah gives His messengers power over whom He wills, and Allah is over all things competent. (Quran 59:6)
In fact, horses are also mentioned indirectly in Surah Al Adiyat, Chapter 100.