{And [remember], when He showed them to you, when you met, as few in your eyes and He made you appear as few in their eyes.} Al-Kalbi said: When the Muslims beheld the polytheists on the day of Badr, they saw them as few; thus they confirmed the vision of the Messenger of Allah. Allah also made the Muslims appear as few in the eyes of the polytheists, so the believers were emboldened against the polytheists, and the polytheists were emboldened against the believers, {so that Allah might accomplish a matter already destined,} meaning: in which was your victory.
﴿وَإِذْ يُرِيكُمُوهُمْ إِذِ الْتَقَيْتُمْ فِي أَعْيُنِكُمْ قَلِيلا وَيُقَلِّلُكُمْ فِي أَعْيُنِهِمْ﴾ قَالَ الْكَلْبِيُّ: إِنَّ الْمُسْلِمِينَ لَمَّا عَايَنُوا الْمُشْرِكِينَ يَوْمَ بَدْرٍ رَأَوْهُمْ قَلِيلا؛ فَصَدَّقُوا رُؤْيَا رَسُولِ اللَّهِ، وَقَلَّلَ اللَّهُ الْمُسْلِمِينَ فِي أَعْيُنِ الْمُشْرِكِينَ، فَاجْتَرَأَ الْمُؤْمِنُونَ عَلَى الْمُشْرِكِينَ، وَاجْتَرَأَ الْمُشْرِكُونَ عَلَى الْمُؤْمِنِينَ ﴿لِيَقْضِيَ الله أمرا كَانَ مَفْعُولا﴾ أَي: فِيهِ نصركم.