"than what was taken from you" — meaning: they had betrayed Allah before — "so He empowered [you] over them," until they became captives at Badr.
Surah al-Anfal from verse 72 to verse 75.
﴿فَقَدْ خَانُوا الله من قبل﴾ يَعْنِي: فَقَدْ كَفَرُوا بِاللَّهِ مِنْ قبل ﴿فَأمكن مِنْهُم﴾ حَتَّى صَارُوا أَسْرَى فِي بَدْرٍ.
سُورَة الْأَنْفَال من الْآيَة (٧٢) إِلَى الْآيَة (٧٥).