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].
App reference: Book 7, Hadith 2
Arabic/English book reference: Book 7, Hadith 895