" And if a woman has reason to fear ill-treatment from her husband or that he might turn away from her" (iv. 128) that it was revealed in case of a woman who had long association with a person (as his wife) and now he intends to divorce her and she says: Do not divorce me, but retain me (as wife in your house) and you are permitted to live with another wife. It is in this context that this verse was revealed.  

عَنْ عَائِشَةَ { وَإِنِ امْرَأَةٌ خَافَتْ مِنْ بَعْلِهَا نُشُوزًا أَوْ إِعْرَاضًا} الآيَةَ قَالَتْ أُنْزِلَتْ فِي الْمَرْأَةِ تَكُونُ عِنْدَ الرَّجُلِ فَتَطُولُ صُحْبَتُهَا فَيُرِيدُ طَلاَقَهَا فَتَقُولُ لاَ تُطَلِّقْنِي وَأَمْسِكْنِي وَأَنْتَ فِي حِلٍّ مِنِّي فَنَزَلَتْ هَذِهِ الآيَةُ  

"Sawdah feared that the Prophet ﷺ was going to divorce her, so she said: 'Do not divorce me, but keep me and give my day to 'Aishah.' So he ﷺ did so, and the following was revealed: Then there is no sin on them both if they make terms of peace between themselves, and making peace is better (4:128). So whatever they agree to make peace in something then it is permissible."  

أَنْ يُطَلِّقَهَا النَّبِيُّ ﷺ فَقَالَتْ لاَ تُطَلِّقْنِي وَأَمْسِكْنِي وَاجْعَلْ يَوْمِي لِعَائِشَةَ فَفَعَلَ فَنَزَلَتْ ( فَلاَ جُنَاحَ عَلَيْهِمَا أَنْ يُصْلِحَا بَيْنَهُمَا صُلْحًا وَالصُّلْحُ خَيْرٌ ) فَمَا اصْطَلَحَا عَلَيْهِ مِنْ شَيْءٍ فَهُوَ جَائِزٌ كَأَنَّهُ مِنْ قَوْلِ ابْنِ عَبَّاسٍ  

[Machine] "That the Prophet ﷺ divorced her, so she said, 'O Messenger of Allah, hold on to me and do not divorce me, and make my day for Aisha.' So he did, and Allah revealed, 'So there is no blame upon either of them for reconciliation. And reconciliation is by far best. And [if] they resolve upon it, then indeed Allah is ever hearing and knowing.' (Quran 4:128)"  

أَنْ يُطَلِّقَهَا النَّبِيُّ ﷺ فَقَالَتْ يَا رَسُولَ اللهِ أَمْسِكْنِي وَلَا تُطَلِّقْنِي وَاجْعَلْ يَوْمِي لِعَائِشَةَ فَفَعَلَ وَأَنْزَلَ اللهُ ﷻ {فَلَا جُنَاحَ} عَلَيْهِمَا أَنْ يُصْلِحَا بَيْنَهُمَا صُلْحًا وَالصُّلْحُ خَيْرٌ فَمَا اصْطَلَحَا عَلَيْهِ مِنْ شَيْءٍ فَهُوَ جَائِزٌ  

[Machine] "Do not divorce me and hold me back, and swear to me whatever you wish, and we will make a fair agreement. Thus was the Sunnah established and the Quran was revealed: 'And if a woman fears from her husband contempt or evasion.' [Surah An-Nisa 128]"  

لَا تُطَلِّقْنِي وَأَمْسِكْنِي وَاقْسِمْ لِي مَا شِئْتَ فَاصْطَلَحَا عَلَى صُلْحٍ فَجَرَتِ السُّنَّةُ بِذَلِكَ وَنَزَلَ الْقُرْآنُ {وَإِنِ امْرَأَةٌ خَافَتْ مِنْ بَعْلِهَا نُشُوزًا أَوْ إِعْرَاضًا} [النساء 128]