Quran 33:53

يَـٰٓأَيُّہَا ٱلَّذِينَ ءَامَنُواْ لَا تَدۡخُلُواْ بُيُوتَ ٱلنَّبِىِّ إِلَّآ أَن يُؤۡذَنَ لَكُمۡ إِلَىٰ طَعَامٍ غَيۡرَ نَـٰظِرِينَ إِنَٮٰهُ وَلَـٰكِنۡ إِذَا دُعِيتُمۡ فَٱدۡخُلُواْ فَإِذَا طَعِمۡتُمۡ فَٱنتَشِرُواْ وَلَا مُسۡتَـٔۡنِسِينَ لِحَدِيثٍۚ إِنَّ ذَٲلِكُمۡ ڪَانَ يُؤۡذِى ٱلنَّبِىَّ فَيَسۡتَحۡىِۦ مِنڪُمۡۖ وَٱللَّهُ لَا يَسۡتَحۡىِۦ مِنَ ٱلۡحَقِّۚ وَإِذَا سَأَلۡتُمُوهُنَّ مَتَـٰعً۬ا فَسۡـَٔلُوهُنَّ مِن وَرَآءِ حِجَابٍ۬ۚ ذَٲلِڪُمۡ أَطۡهَرُ لِقُلُوبِكُمۡ وَقُلُوبِهِنَّۚ وَمَا كَانَ لَڪُمۡ أَن تُؤۡذُواْ رَسُولَ ٱللهِ وَلَآ أَن تَنكِحُوٓاْ أَزۡوَٲجَهُ ۥ مِنۢ بَعۡدِهِۦۤ أَبَدًاۚ إِنَّ ذَٲلِكُمۡ ڪَانَ عِندَ ٱللهِ عَظِيمًا ٥٣

O you who believe, do not enter the prophet’s homes unless you are given permission to eat, nor shall you force such an invitation in any manner. If you are invited, you may enter. When you finish eating, you shall leave; do not engage him in lengthy conversations. This used to hurt the prophet, and he was too shy to tell you. But ALLAH does not shy away from the truth. If you have to ask them (his wives) for something, ask them from behind a barrier. This is purer for your hearts and their hearts. You are not to hurt the messenger of ALLAH. You shall not marry his wives after him, for this would be a gross offense in the sight of ALLAH.