The Messenger of Allah ﷺ said, "Blessing in horses lies in those of reddish-bay color."
حدثنا يحيى بن معين حدثنا حسين بن محمد عن شيبان عن عيسى بن علي عن أبيه
قال رسول الله ﷺ يمن الخيل في شقرها
No references are available.
[Its isnad is hasan] Tirmidhi transmitted it in Jami Tirmidhi, jihad, chapter on what is recommended regarding horses, hadith no. 1695.