The importance of saying SALAAM to a Muslim & returning the greeting: A man asked the Prophet (PBUH): "What sort of deeds or (what qualities of) Islam are good?" He (PBUH) said, “To feed (the poor) & greet those whom you know & those whom you do not know.” [Bukhari Book 2 #12] ~ "When you are greeted with a greeting, greet in return with what is better than it, or (at least) return it equally..." [The Qur'an 4:86