How to answer greetings

وَإِذَا حُيِّيتُم بِتَحِيَّةٍۢ فَحَيُّوا۟ بِأَحْسَنَ مِنْهَآ أَوْ رُدُّوهَآ ۗ إِنَّ ٱللَّهَ كَانَ عَلَىٰ كُلِّ شَىْءٍ حَسِيبًا

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.

إِذْ دَخَلُوا۟ عَلَيْهِ فَقَالُوا۟ سَلَٰمًۭا ۖ قَالَ سَلَٰمٌۭ قَوْمٌۭ مُّنكَرُونَ

Behold, they entered his presence, and said: "Peace!" He said, "Peace!" (and thought, "These seem) unusual people."