We used to eat horse meat during the time of the Messenger of Allah ﷺ.
أخبرنا علي بن حجر قال حدثنا عبيد الله وهو ابن عمرو قال حدثنا عبد الكريم عن عطاء
كنا نأكل لحوم الخيل على عهد رسول الله ﷺ
[Its isnad is sahih] Ibn Majah reported it in the Book of Slaughtered Animals, Chapter on the Meat of Mules, hadith 3197, from the hadith of Abdul-Kareem Jazari, through him, and it is in Al-Kubra, hadith 4842.