Surah An-Nisa Verse 86 - English Translation by Ali Unal
Surah An-Nisaوَإِذَا حُيِّيتُم بِتَحِيَّةٖ فَحَيُّواْ بِأَحۡسَنَ مِنۡهَآ أَوۡ رُدُّوهَآۗ إِنَّ ٱللَّهَ كَانَ عَلَىٰ كُلِّ شَيۡءٍ حَسِيبًا
When (whether traveling or at home, or in war or at peace) you are greeted with a greeting (of peace and goodwill), answer with one better, or (at least) with the same. Surely God keeps account of all things