Sunan Ibn Majah, Book 6, Hadith 1502 (In-Book) ⓘ

It was narrated from Abu Hurairah that the Messenger of Allah said: “Five are the rights of the Muslim: Returning his greeting, accepting his invitation; attending his funeral; visiting the sick; and answering (saying Yarhamuk-Allah) to the one who sneezes, if he praises Allah (says Al-Hamdu Lillah).”

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا مُحَمَّدُ بْنُ بِشْرٍ، عَنْ مُحَمَّدِ بْنِ عَمْرٍو، عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ ‏ "‏ خَمْسٌ مِنْ حَقِّ الْمُسْلِمِ عَلَى الْمُسْلِمِ رَدُّ التَّحِيَّةِ وَإِجَابَةُ الدَّعْوَةِ وَشُهُودُ الْجِنَازَةِ وَعِيَادَةُ الْمَرِيضِ وَتَشْمِيتُ الْعَاطِسِ إِذَا حَمِدَ اللَّهَ ‏" ‏ ‏.‏