33. Al-Ahzab
الأحزاب
52 / 73
لَّا يَحِلُّ لَكَ ٱلنِّسَآءُ مِنۢ بَعْدُ وَلَآ أَن تَبَدَّلَ بِهِنَّ مِنْ أَزْوَٰجٍ وَلَوْ أَعْجَبَكَ حُسْنُهُنَّ إِلَّا مَا مَلَكَتْ يَمِينُكَ ۗ وَكَانَ ٱللَّهُ عَلَىٰ كُلِّ شَىْءٍ رَّقِيبًا
You [Prophet] are not permitted to take any further wives, nor to exchange the wives you have for others, even if these attract you with their beauty. But this does not apply to your slave-girls: God is watchful over all.
33:52