The word ‘Salaam’ is a quality of Allah meaning ‘Peace’. It is not
permissible to greet non-Muslims with ‘Assalaamu Alaykum’.
If they greet you with the Salaam, reply with ‘Wassalaamu alaa man al-tabaa`
al-Hudaa’ (May peace be upon the guided ones).
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai