28. One should not make salaam when greeting a non-Muslim. If a non-Muslim greets one with salaam, then one should reply by merely saying “Wa ‘Alaik” (and upon you), and if many non-Muslims greet one with salaam, one should reply by saying “Wa ‘Alaikum” (and upon you all).

عن أنس بن مالك أن رسول الله صلى الله عليه وسلم قال: إذا سلم عليكم أهل الكتاب فقولوا وعليكم (صحيح مسلم: الرقم 2163)

Hazrat Anas (radhiyallahu ‘anhu) reports that Rasulullah (sallallahu ‘alaihi wasallam) said, “When the Ahl-e-kitaab (Jews and Christians) make salaam to you, then reply by merely saying “Wa ‘alaikum”.”