Surah An-Nisa · Ayah 20

وَإِنْ أَرَدتُّمُ ٱسْتِبْدَالَ زَوْجٍۢ مَّكَانَ زَوْجٍۢ وَءَاتَيْتُمْ إِحْدَىٰهُنَّ قِنطَارًۭا فَلَا تَأْخُذُوا۟ مِنْهُ شَيْـًٔا ۚ أَتَأْخُذُونَهُۥ بُهْتَٰنًۭا وَإِثْمًۭا مُّبِينًۭا

Wa in arattumustib daala zawjim makaana zawjin wa aataitum ihdaahunna qintaaran falaa taakhuzoo minhu shai'aa; ataakhuzoonahoo buhtaannanw wa ismam mubeenaa

But if you want to replace one wife with another and you have given one of them a great amount [in gifts], do not take [back] from it anything. Would you take it in injustice and manifest sin?