Sahih Bukhari
Fighting for the Cause of Allah (Jihaad)
Volume: 004 / Book Number: 052 / Hadith Number: 121
Narrated Abdullah:
The Prophet arranged for a horse race of the horses which had not been made lean; the area of the race was from Ath-Thaniya to the mosque of Bani Zuraiq. (The sub-narrator said, "'Abdullah bin 'Umar was amongst those who participated in that horse race.").