Abu Hurairah (May Allah be pleased with him) reported

The Messenger of Allah (ﷺ) 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]."

[Al-Bukhari and Muslim].