Sunan Abi Dawud Book 15, Hadith 102
while she was on a journey along with the Messenger of Allah (ﷺ): I had a race with him (the Prophet) and I outstripped him on my feet. When I became fleshy, (again) I had a race with him (the Prophet) and he outstripped me. He said: This is for that outstripping.
The Prophet (ﷺ) used to hold a race between horses and kept the one in the fifth year at a long distance.
The Prophet (ﷺ) said: If one enters a horse with two others when he is not certain that it cannot be beaten, it is not gambling; but when one enters a horse with two others when he is certain it cannot be beaten, it is gambling.