اشْتَرَوْاْ بِـَايَـتِ اللَّهِ ثَمَنًا قَلِيلاً

(They have purchased with the Ayat of Allah a little gain,) idolators exchanged following the Ayat of Allah with the lower affairs of life that they indulged in,

فَصَدُّواْ عَن سَبِيلِهِ

وَأَقَامُوا الصَّلَاةَ وَآتَوُا الزَّكَاةَ فَإِخْوَانُكُمْ فِي الدِّينِ (Then, if they repent and establish salah and pay zakah, they are your brothers in faith).

Here we are being told that once an enemy - no matter how deadly and no matter how hurtful he has been - becomes a Muslim, things change dramatically. Allah Ta` ala forgives his past sins, all of them. So, it becomes obligatory on Muslims too that they should forget the past, start afresh, take them as their brothers in faith and do whatever it takes to fulfill the rights enjoined under such relationship.