And remember when ye met, He showed them to you as few in your eyes, and He made you appear as contemptible in their eyes: that Allah might accomplish a matter already enacted. For to Allah do all questions go back (for decision). Al-Anfal 8:44 ⧉
Tafsir:
At Badr the Quraysh had a large army. Had the Muslims seen their real numbers, some of them would have said that they should fight, while others would have asked not to fight. In this way differences would have cropped up and the real task would have remained unfinished. So, God showed their numbers to Muslims as fewer while he showed the number of Muslims to the Quraysh as more. In this way it was possible for the Muslims to fight fearlessly. When God wants a task to be performed, He sends help and arranges for its completion. The events that occur during the course of action occur at God’s behest, so that He may judge the reaction of the person concerned to the conditions set by Him.