It was narrated that 'Aishah said:"This Verse 'And making peace is better.' was revealed concerning a man who had been married to a woman for a long time, and she had given birth to his children and he wanted to exchange her (for a new wife). She agreed that he would stay with her (the new wife) and would not give her (the first wife) a share of his time. (i.e.) not spend the nights with her)."
حَدَّثَنَا حَفْصُ بْنُ عَمْرٍو، حَدَّثَنَا عُمَرُ بْنُ عَلِيٍّ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، . أَنَّهَا قَالَتْ نَزَلَتْ هَذِهِ الآيَةُ {وَالصُّلْحُ خَيْرٌ} فِي رَجُلٍ كَانَتْ تَحْتَهُ امْرَأَةٌ قَدْ طَالَتْ صُحْبَتُهَا وَوَلَدَتْ مِنْهُ أَوْلاَدًا فَأَرَادَ أَنْ يَسْتَبْدِلَ بِهَا فَرَاضَتْهُ عَلَى أَنْ تُقِيمَ عِنْدَهُ وَلاَ يَقْسِمَ لَهَا .
IbnMaja
The Chapters on Marriage • Hadith 1974