The gist of the fourth verse (278): يَا أَيُّهَا الَّذِينَ آمَنُوا اتَّقُوا اللَّـهَ وَذَرُ‌وا مَا بَقِيَ مِنَ الرِّ‌بَا إِن كُنتُم مُّؤْمِنِينَ those who believe, fear Allah and give up what still remains of the riba if you are believers" is that, after the revelation that prohibited riba, the giving and taking of the amount of ربا riba that remained due against anyone was also prohibited.

Explaining this, it can be said that ربا riba was rampant all over Arabia before it was prohibited by revelation. When verses earlier than the present one brought forth its prohibition, Muslims - following their Qur'an-oriented habit - abandoned all their ربا riba-related dealings. But some people had claims of unpaid ربا riba amounts on some others. In that connection, it so happened that Banu Thaqif and Banu Makhzum, two Arab tribes, had mutual ربا riba dealings and people from Banu Thaqif had claims of unpaid ربا riba amounts against Banu Makhznm. When Banu Makhzum became Muslims they, after having made their commitment to Islam, thought it to be impermissible to pay back the amount of ربا riba due. On the other side were Banu Thaqif; their people started pressing their claim. Since these people had become Muslims, but did have a mutual peace agreement, the people of Banu Makhzum told them that they had now entered the fold of Islam and had no intention of spending their Islamic earnings in paying off ربا riba.

This dispute rose in Makkah. That was a time after the conquest of Makkah. Sayyidna Muadh ؓ (according to another report, Sayyidna ` Attab ibn 'Asid ؓ was the Amir of Makkah, governor of the city, appointed by the Holy Prophet ﷺ . He reported this dispute in writing to him requesting his guidance. It was in this background that this verse of the Qur'an was revealed, the gist of which is that all previous dealings involving ربا riba should be terminated after entry into the fold of Islam, also no previous riba amount should be realized. The principal was all that could be taken.

When this Islamic law was enforced, the Muslims were already bound by it. The non-Muslim tribes who had accepted the Islamic law as party in peace treaties, they too, were bound by it. But, in spite of this, when the Holy Prophet ﷺ announced this law in his famous address of the Last Hajj (حجۃ الوداع), he made it a point to say that this law does not carry behind it the financial interest of any individual, or nation, or Muslims themselves. This has been brought into force to reconstruct, reform and better the whole humanity. Therefore, first of all, we let go large amounts of ربا riba owed by non-Muslims to Muslims. Now they too should have no excuse in leaving off the amount of ربا riba they claimed. As he said in his Address:

الا اَن کل ربا کان فی الجاھلیہ موضوع عنکم کلہ لکم رؤس اموالکم لا تظلمون ولا تظلمون و اول ربا موضوع ربا العباس بن عبد المطلب کلہ (ابن کثیر بحوالہ ابن ابی حاتم)

which means that the ربا riba content of all ربا riba dealings made in the age

of ignorance stood forsaken. Now everyone will get the principal and no one will get the extra amount of ربا riba. 'Neither shall you be able to do injustice to anyone by charging an increased amount, nor shall anyone be able to do injustice to you by decreasing the amount of your principal.' And the first ربا riba that was surrendered was the ربا riba of Sayyidna ` Abbas ibn ` Abd al-Muttalib ؓ ، large amounts of which were due on non-Muslims in the form of ربا riba.

The subject verse refers to this happening and sets out the injunction to leave off all standing ربا riba amounts.

As the verse opens addressed to Muslims, they were first given the command of اتَّقُوا اللَّـهَ that is, 'fear Allah.' Given after that was the injunction covering the real issue. This is the same unique style of the Qur'an which distinguishes it from all the law books of the world. When a law, which is somewhat difficult to act upon, is given, it has the prefixes and suffixes of accountability of deeds before Allah Almighty, and the punishment and reward of the Hereafter, so that Muslim minds and hearts become prepared to act upon it; the injunction is announced after that. Here too, the forsaking of the amount of matured ربا riba could weigh heavy on human disposition, therefore, said first was اتَّقُوا اللَّـهَ (fear Allah). After that, came the injunction: وَذَرُ‌وا مَا بَقِيَ مِنَ الرِّ‌بَا that is, 'leave off ربا riba that remains.' Towards the end of the verse it was said: إِن كُنتُم مُّؤْمِنِين that is, 'if you are believers.' Here it was indicated that ‘Iman (faith, belief) requires that Divine injunctions should be followed faithfully. Acting otherwise negates ایمان 'Iman. Since this injunction was somewhat heavy on temperaments, اتَّقُوا اللَّـهَ (Fear Allah) was added before it, and; إِن كُنتُم مُّؤْمِنِين (If you are believers) after it.