He reported God’s messenger as saying, “A Muslim has six duties towards another Muslim.” When asked what they were he replied, “When you meet him salute him ; when he issues an invitation to you, accept it; when he asks your advice give it to him ; when he sneezes and praises God say, ‘God have mercy on you’; when he is ill visit him ; and when he dies follow him to the grave.” Muslim transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «حَقُّ الْمُسْلِمِ عَلَى الْمُسْلِمِ سِتٌّ» . قِيلَ: مَا هُنَّ يَا رَسُولَ اللَّهِ؟ قَالَ: «إِذَا لَقِيتَهُ فَسَلِّمْ عَلَيْهِ وَإِذَا دَعَاكَ فَأَجِبْهُ وَإِذَا اسْتَنْصَحَكَ فَانْصَحْ لَهُ وَإِذَا عَطَسَ فَحَمِدَ اللَّهَ فَشَمِّتْهُ وَإِذَا مَرِضَ فَعُدْهُ وَإِذَا مَاتَ فَاتَّبِعْهُ» . رَوَاهُ مُسلم
sunnah.com