Jihad (Kitab Al-Jihad)
Dawud :: Book 14 : Hadith 2573
Narrated AbuHurayrah:
The Prophet (peace_be_upon_him) 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.