O you who have believed, do not enter houses other than your own houses until you ascertain welcome and greet their inhabitants. That is best for you; perhaps you will be reminded.  

يَا أَيُّهَا الَّذِينَ آمَنُوا لَا تَدْخُلُوا بُيُوتًا غَيْرَ بُيُوتِكُمْ حَتَّىٰ تَسْتَأْنِسُوا وَتُسَلِّمُوا عَلَىٰ أَهْلِهَا ۚ ذَٰلِكُمْ خَيْرٌ لَكُمْ لَعَلَّكُمْ تَذَكَّرُونَ  

And if you do not find anyone therein, do not enter them until permission has been given you. And if it is said to you, "Go back," then go back; it is purer for you. And Allah is Knowing of what you do.  

فَإِنْ لَمْ تَجِدُوا فِيهَا أَحَدًا فَلَا تَدْخُلُوهَا حَتَّىٰ يُؤْذَنَ لَكُمْ ۖ وَإِنْ قِيلَ لَكُمُ ارْجِعُوا فَارْجِعُوا ۖ هُوَ أَزْكَىٰ لَكُمْ ۚ وَاللَّهُ بِمَا تَعْمَلُونَ عَلِيمٌ  

There is no blame upon you for entering houses not inhabited in which there is convenience for you. And Allah knows what you reveal and what you conceal.  

لَيْسَ عَلَيْكُمْ جُنَاحٌ أَنْ تَدْخُلُوا بُيُوتًا غَيْرَ مَسْكُونَةٍ فِيهَا مَتَاعٌ لَكُمْ ۚ وَاللَّهُ يَعْلَمُ مَا تُبْدُونَ وَمَا تَكْتُمُونَ