﴿ وَإِذْ يُرِيكُمُوهُمْ إِذِ ٱلْتَقَيْتُمْ فِىٓ أَعْيُنِكُمْ قَلِيلًۭا وَيُقَلِّلُكُمْ فِىٓ أَعْيُنِهِمْ لِيَقْضِىَ ٱللَّهُ أَمْرًۭا كَانَ مَفْعُولًۭا ۗ وَإِلَى ٱللَّهِ تُرْجَعُ ٱلْأُمُورُ ﴾

“And so, when you met in battle, He made them appear as few in your eyes -just as He made you appear as of little account in their eyes - so that God might accomplish a thing [which He willed] to be done: for all things go back to God [as their source].”

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.