From Sahih Bukhari (Hadith 2969):
Narrated Anas bin Malik:Once the people got frightened, so Allah's Messenger (ﷺ) rode a slow horse belonging to Abu Talha, and he set out all alone, making the horse gallop. Then the people rode, making their horses gallop after him. On his return he said, "Don't be afraid (there is nothing to be afraid of) (and I have found) this horse a very fast one." That horse was never excelled in running hence forward. (Qastalani Vol)
Reference: Bukhari 2969