8:42 And when you were encamped on the nearside and they (the unbelievers) on the farther side, with the caravan below, had you made an appointment with them, you would have surely failed to keep it; but Allah sought to accomplish what He had ordained, so that by clear evidence, he who was destined to perish might perish, and he who was destined to live might live. Surely, Allah is Hearing, Knowing.
8:43 And when Allah made them appear to you in a vision as a small band, had He showed them to you as many, your courage would have failed you and you would have quarreled over the affair. But Allah saved; He knows the inner most thoughts in the chests.
8:44 And when you met them, He showed them in your eyes as being few, and decreased (your number) in their eyes so that Allah might determine what was ordained. To Allah all matters return.