Sunan Abi Dawud Book 15, Hadith 97
My foster-father said to me - he was one of Banu Murrah ibn Awf, and he was present in that battle, the battle of Mu'tah: By Allah, as if I am seeing Ja'far who jumped from his reddish horse and hamstrung it; he then fought with the people until he was killed.
Abu Dawud said: The tradition is not strong.
While the Messenger of Allah (ﷺ) was walking a man who had an ass came to him and said: Messenger of Allah, ride; and the man moved to the back of the animal. The Messenger of Allah (ﷺ) said: No, you have more right to ride in front on your animal than me unless you grant that right to me. He said: I grant it to you. So he mounted.
The Prophet (ﷺ) said: Wagers are allowed only for racing camels, or horses or shooting arrows.