"The believer owes six duties toward his fellow believer: To visit him when he is sick, to attend his funeral when he dies, to accept his invitation, to greet him with Salam when he meets him, to reply to him (say: Yarhamuk Allah, may Allah have mercy on you) when he sneezes and to be sincere to him, whether he is absent or present." (Hasan).  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لِلْمُؤْمِنِ عَلَى الْمُؤْمِنِ سِتُّ خِصَالٍ يَعُودُهُ إِذَا مَرِضَ وَيَشْهَدُهُ إِذَا مَاتَ وَيُجِيبُهُ إِذَا دَعَاهُ وَيُسَلِّمُ عَلَيْهِ إِذَا لَقِيَهُ وَيُشَمِّتُهُ إِذَا عَطَسَ وَيَنْصَحُ لَهُ إِذَا غَابَ أَوْ شَهِدَ  

“The Muslim has four things due from the Muslim: He should answer [by saying Yarhamuk-Allah (may Allah have mercy on you)] to him if he sneezes (and says Al-Hamdulillah); he should accept his invitation if he invites him; he should attend his funeral if he dies; and he should visit him if he falls sick.”  

عَنِ النَّبِيِّ ﷺ قَالَ لِلْمُسْلِمِ عَلَى الْمُسْلِمِ أَرْبَعُ خِلاَلٍ يُشَمِّتُهُ إِذَا عَطَسَ وَيُجِيبُهُ إِذَا دَعَاهُ وَيَشْهَدُهُ إِذَا مَاتَ وَيَعُودُهُ إِذَا مَرِضَ