لَوْلَا كِتَابٌ مِنَ اللَّهِ سَبَقَ لَمَسَّكُمْ فِيمَا أَخَذْتُمْ عَذَابٌ عَظِيمٌ ﴿۶۸﴾ فَكُلُوا مِمَّا غَنِمْتُمْ حَلَالًا طَيِّبًا وَاتَّقُوا اللَّهَ إِنَّ اللَّهَ غَفُورٌ رَحِيمٌ ﴿۶۹﴾ يَا أَيُّهَا النَّبِيُّ قُلْ لِمَنْ فِي أَيْدِيكُمْ مِنَ الْأَسْرَى إِنْ يَعْلَمِ اللَّهُ فِي قُلُوبِكُمْ خَيْرًا يُؤْتِكُمْ خَيْرًا مِمَّا أُخِذَ مِنْكُمْ وَيَغْفِرْ لَكُمْ وَاللَّهُ غَفُورٌ رَحِيمٌ ﴿۷۰﴾

﴾68﴿ Law laa Kitaabum minal laahi sabaqa lamassakum fee maaa akhaztum 'azaabun 'azeem
﴾69﴿ Fakuloo mimmaa ghanimtum halaalan taiyibaa; watta qullaah; innal laaha Ghafoorur Raheem
﴾70﴿ Yaaa aiyuhan Nabiyyu qul liman feee aideekum minal asraaa iny-ya'lamillahu fee quloobikum khairany yu'tikum khayram mimmaaa ukhiza minkum wa yaghfir lakum; wallaahu Ghafoorur Raheem

﴾68﴿ If it were not for a decree from Allah Almighty that has already been decided, a great punishment would have befallen you because of the wealth you took (in ransoming the prisoners)
﴾69﴿ So eat from what you have taken as booty, lawful and good, and fear Allah. Indeed, He is Oft-Forgiving, Most Merciful
﴾70﴿ O Prophet, say Those who are in your hands of the captives, if Allah knows there is faith in your hearts, May He give you better than what has been taken from you and forgive you. And Allah is Oft-Forgiving, Most Merciful

[68] This is the answer to a question: when the ransom was taken, did they become sinful, and should punishment have come upon them?
The essence of the answer is that if Allah had not already set a law beforehand, then indeed punishment would have occurred.
However, Allah had already established a rule—that He does not punish anyone until He first sends down the command.
Another principle is that Allah has made war booty (ghanimah) lawful for this ummah.
And another rule is that Allah has forgiven all those who participated in the Battle of Badr.
[69] Since some of the noble Companions, after this admonishment, began to feel aversion toward accepting ransom, this verse was revealed to remove that aversion—saying: do not dislike it, for this is war booty, and it is lawful.
In the phrase "so eat..." (فَكُلُوا), the "fa" indicates causation, and the conditional clause is omitted—meaning: "When the spoils of war were made lawful for you, then eat from them."
In other words, the verse is saying: now that it has been permitted, there is no harm in benefiting from it.
[70] This is the thirteenth rule for the commander. Its essence is that, among the captives, someone may claim to have accepted faith in order to escape paying ransom.
In such a case, he should be told: ransom is still required from you, and if your claim of faith is true, then Allah will grant you a great reward in return.
This very situation occurred at the Battle of Badr with ʿAbbās (may Allah be pleased with him), though the verse itself is general.
The wisdom behind this rule is that if a person could avoid ransom simply by claiming faith, the entire system of ransom would become meaningless and ineffective.