If a guest sees something bad, he should go back Sunan Ibn Majah 3360
Arabic hadith text
حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ عَبْدِ اللَّهِ الْجَزَرِيُّ، حَدَّثَنَا عَفَّانُ بْنُ مُسْلِمٍ، حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ، حَدَّثَنَا سَعِيدُ بْنُ جُمْهَانَ، حَدَّثَنَا سَفِينَةُ أَبُو عَبْدِ الرَّحْمَنِ، أَنَّ رَجُلاً، أَضَافَ عَلِيَّ بْنَ أَبِي طَالِبٍ فَصَنَعَ لَهُ طَعَامًا فَقَالَتْ فَاطِمَةُ لَوْ دَعَوْنَا النَّبِيَّ ـ صلى الله عليه وسلم ـ فَأَكَلَ مَعَنَا . فَدَعَوْهُ فَجَاءَ فَوَضَعَ يَدَهُ عَلَى عِضَادَتَىِ الْبَابِ فَرَأَى قِرَامًا فِي نَاحِيَةِ الْبَيْتِ فَرَجَعَ فَقَالَتْ فَاطِمَةُ لِعَلِيٍّ الْحَقْ فَقُلْ لَهُ مَا رَجَعَكَ يَا رَسُولَ اللَّهِ قَالَ " إِنَّهُ لَيْسَ لِي أَنْ أَدْخُلَ بَيْتًا مُزَوَّقًا "
Translation
Safinah,Abu ‘Abdur-Rahman, narrated that a man visited ‘Ali bin AbuTaliband he made some food for him.* Fatimah said
“Why don’t weinvite the Prophet (ﷺ) to eat with us?” So they invited him andhecame. He put his hand on the doorpost of the house and saw a thincurtain in the corner of the house, so he went back. Fatimah said to‘Ali: “Go and catch up with him, and ask him: ‘What made you goback,O Messenger of Allah?” He said: “I do not enter awell-decoratedhouse.”