وَإِذَا حُيِّيتُم بِتَحِيَّةٍ فَحَيُّواْ بِأَحْسَنَ مِنْهَآ أَوْ رُدُّوهَآۗ إِنَّ ٱللَّهَ كَانَ عَلَىٰ كُلِّ شَىْءٍ حَسِيبًا ٨٦
When ye are greeted with a greeting, greet ye with a better than it or return it. Lo! Allah taketh count of all things.