Riyad as-Salihin, Book 7, Hadith 895 (In-Book) ⓘ

Abu Hurairah (May Allah be pleased with him) reported: The Messenger of Allah 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].

وعن أبي هريرة رضي الله عنه أن رسول الله صلى الله عليه وسلم قال‏:‏ ‏"‏حق المسلم علي المسلم خمس‏:‏ رد السلام، وعيادة المريض، واتباع الجنائز، وإجابة الدعوة، وتشميت العاطس” ‏(‏‏(‏متفق عليه‏)‏‏)‏ ‏.‏