Sura al-Nisāʾ 4:20

وَإِنْ أَرَدتُّمُ ٱسْتِبْدَالَ زَوْجٍ مَّكَانَ زَوْجٍ وَءَاتَيْتُمْ إِحْدَىٰهُنَّ قِنطَارًا فَلَا تَأْخُذُوا۟ مِنْهُ شَيْـًٔا أَتَأْخُذُونَهُۥ بُهْتَٰنًا وَإِثْمًا مُّبِينًا

wa-in aradttumu istibdāla zawjin makāna zawjin wa-ātaytum iḥdahunna qinṭāran fa-lā takhudhū minhu shayʾan a-taʾkhudhūnahu buhtānan wa-ithman mubīnan

But if ye decide to take one wife in place of another, even if ye had given the latter a whole treasure for dower, Take not the least bit of it back: Would ye take it by slander and manifest wrong?