Surah Al-Baqarah, verse 229

ٱلطَّلَـٰقُ مَرَّتَانِ ۖ فَإِمْسَاكٌۢ بِمَعْرُوفٍ أَوْ تَسْرِيحٌۢ بِإِحْسَـٰنٍ ۗ وَلَا يَحِلُّ لَكُمْ أَن تَأْخُذُوا۟ مِمَّآ ءَاتَيْتُمُوهُنَّ شَيْـًٔا إِلَّآ أَن يَخَافَآ أَلَّا يُقِيمَا حُدُودَ ٱللَّهِ ۖ فَإِنْ خِفْتُمْ أَلَّا يُقِيمَا حُدُودَ ٱللَّهِ فَلَا جُنَاحَ عَلَيْهِمَا فِيمَا ٱفْتَدَتْ بِهِۦ ۗ تِلْكَ حُدُودُ ٱللَّهِ فَلَا تَعْتَدُوهَا ۚ وَمَن يَتَعَدَّ حُدُودَ ٱللَّهِ فَأُو۟لَـٰٓئِكَ هُمُ ٱلظَّـٰلِمُونَ ﴿٢٢٩﴾

2:229 Divorce may be pronounced twice; then either retaining in all kindness, or separating in the best way. It is not lawful for you to take back anything that you have given them [of dowry], except when they both fear that they would not be able to maintain the limits ordained by Allah. So if you fear that they would not be able to maintain the limits set by Allah, then there is no sin upon either of them if she opts to give something for her release. These are the limits ordained by Allah, so do not exceed them; whosoever exceeds the limits ordained by Allah, it is they who are the wrongdoers