Qur'an 25:63

وَعِبَادُ ٱلرَّحْمَـٰنِ ٱلَّذِينَ يَمْشُونَ عَلَى ٱلْأَرْضِ هَوْنًا وَإِذَا خَاطَبَهُمُ ٱلْجَـٰهِلُونَ قَالُوا۟ سَلَـٰمًا

The (faithful) slaves of the Beneficent are they who walk upon the earth modestly, and when the foolish ones address them answer: Peace;