Anas reported that the Prophet, may Allah bless him and grant himpeace, was the best of people, the most generous of people and most courageousof people. One night the people of Madina were alarmed by a noise and thepeople went towards its source. The Prophet, may Allah bless him and granthim peace, met them, having already reached the source of the noise beforethem and he was saying, "Do not be alarmed. Do not be alarmed." He wasriding a horse belonging to Abu Talha without a saddle and a sword washung around his neck. He said, "I found it (the horse) like a great river"or it was a great river (meaning its speed).
English reference: Book 14, Hadith 303
Arabic reference: Book 1, Hadith 303