Musnad Ishaq

Benefits:
Regarding the first part of the mentioned narration, Allah the Exalted says:
﴿یٰٓاَیُّهَا النَّبِیُّ حَرِّضِ الْمُؤْمِنِیْنَ عَلَی الْقِتَالِ اِنْ یَّکُنْ مِّنْکُمْ عِشْرُوْنَ صٰبِرُوْنَ یَغْلِبُوْا مِائَتَیْنِ وَ اِنْ یَّکُنْ مِّنْکُمْ مِّائَةٌ یَّغْلِبُوْٓا اَلْفَا مِّنَ الَّذِیْنَ کَفَرُوْا بِاَنَّهُمْ قَوْمٌ لَّا یَفْقَهُوْنَ() اَلْئٰنَ خَفَّفَ اللّٰهُ عَنْکُمْ وَ عَلِمَ اَنَّ فِیْکُمْ ضَعْفًا فَاِنْ یَّکُنْ مِّنْکُمْ مِّائَةٌ صَابِرَةٌ یَّغْلِبُوْا مِائَتَیْنِ وَ اِنْ یَّکُنْ مِّنْکُمْ اَلْفٌ یَّغْلِبُوْٓا اَلْفَیْنِ بِاِذْنِ اللّٰهِ وَ اللّٰهُ مَعَ الصَّبِرِیْنَ﴾ (Al-Anfal: 6, 66)
“O Prophet! Urge the believers to fight. If there are twenty steadfast among you, they will overcome two hundred, and if there are a hundred among you, they will overcome a thousand of those who disbelieve, because they are a people who do not understand. Now Allah has lightened your burden, for He knows that there is weakness among you. So if there are a hundred steadfast among you, they will overcome two hundred, and if there are a thousand among you, they will overcome two thousand by Allah’s permission. And Allah is with the steadfast.”

The second part of the narration: In the Battle of Badr, seventy disbelievers were killed and seventy were taken captive. Since this was the first battle between disbelief and Islam, what course of action should be taken regarding the captives? The rulings concerning them were not yet fully clear, so the Messenger of Allah sallallahu alayhi wa sallam consulted Sayyiduna Abu Bakr, Sayyiduna Umar, and Sayyiduna Ali radi Allahu anhum regarding what should be done with these captives. Sayyiduna Abu Bakr radi Allahu anhu said: O Messenger of Allah sallallahu alayhi wa sallam! We are all cousins and relatives. Therefore, my opinion is that you take ransom from them; the benefit of this will be that with this wealth, our defensive strength against the disbelievers will be reinforced. The second benefit is that perhaps Allah will guide these captives to Islam.

When Sayyiduna Umar radi Allahu anhu was consulted, he advised that in order to break the strength and power of disbelief, it is necessary to kill these captives, because they are the leaders of disbelief and the disbelievers. If they are set free, they will conspire against Islam and the Muslims. In any case, the Messenger of Allah sallallahu alayhi wa sallam preferred the opinion of Sayyiduna Abu Bakr radi Allahu anhu and released them after taking ransom. Then Allah, the Possessor of Majesty, revealed these verses:
﴿مَا کَانَ لِنَبِیٍّ اَنْ یَّکُوْنَ لَهٗٓ اَسْرٰی حَتّٰی یُثْخِنَ فِی الْاَرْضِ تُرِیْدُوْنَ عَرَضَ الدُّنْیَا وَاللّٰهُ یُرِیْدُ الْاٰخِرَةَ وَاللّٰهُ عَزِیْزٌ حَکِیْمٌ() لَوْ لَا کِتٰبٌ مِّنَ اللّٰهِ سَبَقَ لَمَسَّکُمْ فِیْمَآ اَخَذْتُمْ عَذَابٌ عَظِیْمٌ﴾ (Al-Anfal: 67, 68)
“It is not for a Prophet to have captives until he has thoroughly subdued (the enemy) in the land. You desire the goods of this world, but Allah desires the Hereafter. And Allah is Mighty, Wise. If it had not been for a decree from Allah that had already preceded, a great punishment would have touched you for what you took.”

That is, Allah, the Possessor of Majesty, wanted that there should not have been haste in taking captives, but rather that the disbelievers should have been slain and much bloodshed should have occurred; after that, ﴿فَاَمَّا مَنًّا بَعْدُ وَاِمَّا فِدَاءً﴾ (Muhammad: 4) “To show favor (by releasing them) or to take ransom are matters for later.”

﴿لَوْ لَا کِتٰبٌ مِّنَ اللّٰهِ سَبَقَ لَمَسَّکُمْ فِیْمَآ اَخَذْتُمْ عَذَابٌ عَظِیْمٌ﴾ (Al-Anfal: 68)
The commentators write: Its meaning is that war booty (mal-e-ghanīmah) was made lawful for the Muslims, although it was not lawful for previous communities. If it had not been decreed as lawful for you in destiny, then because you released (the captives) after taking ransom, a great punishment would have afflicted you.

The third and final part of the narration: Sayyiduna Abbas radi Allahu anhu was a Muslim, but he lived in Makkah Mukarramah and had not yet openly declared his Islam. He came as a captive in the Battle of Badr. When Sayyiduna Abbas radi Allahu anhu declared his Islam, Allah, the Possessor of Majesty, revealed this verse:
﴿یٰٓاَیُّهَا النَّبِیُّ قُلْ لِّمَنْ فِیْٓ اَیْدِیْکُمْ مِّنَ الْاَسْرٰٓی اِنْ یَّعْلَمِ اللّٰهُ فِیْ قُلُوْبِکُمْ خَیْرًا یُّؤْتِکُمْ خَیْرًا مِّمَّآ اُخِذَ مِنْکُمْ وَ یَغْفِرْلَکُمْ وَ اللّٰهُ غَفُوْرٌ رَّحِیْمٌ﴾ (Al-Anfal: 70)
“O Prophet! Say to those captives who are in your hands: If Allah knows any good in your hearts, He will give you better than what was taken from you and will forgive you. And Allah is Forgiving, Merciful.”

Sayyiduna Abbas radi Allahu anhu was later abundantly blessed by Allah, the Possessor of Majesty, with worldly wealth and riches.