Forbidden to marry wives of the Prophet

ٱلنَّبِىُّ أَوْلَىٰ بِٱلْمُؤْمِنِينَ مِنْ أَنفُسِهِمْ ۖ وَأَزْوَٰجُهُۥٓ أُمَّهَٰتُهُمْ ۗ وَأُو۟لُوا۟ ٱلْأَرْحَامِ بَعْضُهُمْ أَوْلَىٰ بِبَعْضٍۢ فِى كِتَٰبِ ٱللَّهِ مِنَ ٱلْمُؤْمِنِينَ وَٱلْمُهَٰجِرِينَ إِلَّآ أَن تَفْعَلُوٓا۟ إِلَىٰٓ أَوْلِيَآئِكُم مَّعْرُوفًۭا ۚ كَانَ ذَٰلِكَ فِى ٱلْكِتَٰبِ مَسْطُورًۭا

The Prophet is closer to the Believers than their own selves, and his wives are their mothers. Blood-relations among each other have closer personal ties, in the Decree of Allah. Than (the Brotherhood of) Believers and Muhajirs: nevertheless do ye what is just to your closest friends: such is the writing in the Decree (of Allah).

يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ لَا تَدْخُلُوا۟ بُيُوتَ ٱلنَّبِىِّ إِلَّآ أَن يُؤْذَنَ لَكُمْ إِلَىٰ طَعَامٍ غَيْرَ نَٰظِرِينَ إِنَىٰهُ وَلَٰكِنْ إِذَا دُعِيتُمْ فَٱدْخُلُوا۟ فَإِذَا طَعِمْتُمْ فَٱنتَشِرُوا۟ وَلَا مُسْتَـْٔنِسِينَ لِحَدِيثٍ ۚ إِنَّ ذَٰلِكُمْ كَانَ يُؤْذِى ٱلنَّبِىَّ فَيَسْتَحْىِۦ مِنكُمْ ۖ وَٱللَّهُ لَا يَسْتَحْىِۦ مِنَ ٱلْحَقِّ ۚ وَإِذَا سَأَلْتُمُوهُنَّ مَتَٰعًۭا فَسْـَٔلُوهُنَّ مِن وَرَآءِ حِجَابٍۢ ۚ ذَٰلِكُمْ أَطْهَرُ لِقُلُوبِكُمْ وَقُلُوبِهِنَّ ۚ وَمَا كَانَ لَكُمْ أَن تُؤْذُوا۟ رَسُولَ ٱللَّهِ وَلَآ أَن تَنكِحُوٓا۟ أَزْوَٰجَهُۥ مِنۢ بَعْدِهِۦٓ أَبَدًا ۚ إِنَّ ذَٰلِكُمْ كَانَ عِندَ ٱللَّهِ عَظِيمًا

O ye who believe! Enter not the Prophet's houses,- until leave is given you,- for a meal, (and then) not (so early as) to wait for its preparation: but when ye are invited, enter; and when ye have taken your meal, disperse, without seeking familiar talk. Such (behaviour) annoys the Prophet: he is ashamed to dismiss you, but Allah is not ashamed (to tell you) the truth. And when ye ask (his ladies) for anything ye want, ask them from before a screen: that makes for greater purity for your hearts and for theirs. Nor is it right for you that ye should annoy Allah's Messenger, or that ye should marry his widows after him at any time. Truly such a thing is in Allah's sight an enormity.