وَإِذَا حُيِّيتُم بِتَحِيَّةٖ فَحَيُّواْ بِأَحۡسَنَ مِنۡهَآ أَوۡ رُدُّوهَآۗ إِنَّ ٱللَّهَ كَانَ عَلَىٰ كُلِّ شَيۡءٍ حَسِيبًا
Wa izaa huyyeetum bitahaiyyatin fahaiyoo bi ahsana minhaaa aw ruddoohaa; innal laaha kaana 'alaa kulli shai'in Haseeba
When a (courteous) greeting is offered you, meet it with a greeting still more courteous, or (at least) of equal courtesy. Allah takes careful account of all things.
— An-Nisa' (ٱلنِّسَاء), 4:86
