Abu Hurairah RA reported: The Messenger of Allah (sallallaahu alayhi wa sallam) said, “Every Muslim has five rights over another Muslim (i.e. he has to perform five duties for another Muslim): to return the greetings, to visit the sick, to accompany funeral processions, to accept an invitation, to respond to the sneezer (i.e., to say: ‘Yarhamuk-Allah (may Allah bestow His Mercy on you)’ when the sneezer praises Allah).”
(Bukhari and Muslim)
