Sahih Bukhari Volume 4, Book 52, Hadith Number 109.

Narated By Anas bin Malik : Once there was a feeling of fright in Medina, so the Prophet borrowed a horse belonging to us called Mandub (and he rode away on it). (When the Prophet returned) he said, “I have not seen anything of fright and I found it (i.e. this horse) very fast.”