Musnad Ahmad 32:552

Yunus narrated to us, Hammad—meaning Ibn Zayd—narrated to us, from Thabit, from Anas, who said: "The Messenger of Allah (ﷺ) was the most handsome of people, the most generous of people, and the most courageous of people." He said: The people of Medina were once alarmed one night, so he set out toward the sound. The Messenger of Allah (ﷺ) returned having investigated the sound for them, while he was upon a horse belonging to Abu Talha that was bare, with no saddle upon it, and the sword was around his neck. He was saying to the people: "Do not be alarmed, do not be alarmed." He said to the horse: "We found it to be a sea, and it is indeed a sea." Anas said: "The horse had been slow before that, but it was never outrun after that."