Bukhari :: Book 2 :: Volume 14 :: Hadith 65
Ibn Umar said something similar to Mujahid's saying: Whenever (Muslims and non-Muslims) stand face to face in battle, the Muslims can pray while standing. Ibn Umar added, "The Prophet said, 'If the number of the enemy is greater than the Muslims, they can pray while standing or riding (individually).' "
Source materials are from the University of Southern California MSA site|
Hadith eBooks converted from Imaan Star