عَنْ أَبِي هُرَيْرَةَ رضى الله عنه
قَالَ رَسُولُ اَللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ -«حَقُّ اَلْمُسْلِمِ عَلَى اَلْمُسْلِمِ سِتٌّ: إِذَا لَقِيتَهُ فَسَلِّمْ عَلَيْهِ، وَإِذَا دَعَاكَ فَأَجِبْهُ، وَإِذَا اِسْتَنْصَحَكَ فَانْصَحْهُ، وَإِذَا عَطَسَ فَحَمِدَ اَللَّهَ فَسَمِّتْهُ وَإِذَا مَرِضَ فَعُدْهُ، وَإِذَا مَاتَ فَاتْبَعْهُ»
“A Muslim has six duties towards other Muslims: When you meet him, you should salute him; when he invites you, accept his invitation; when he asks for your advice, give it to him; when he sneezes and praises Allah, say May Allah have mercy on you; when he is ill, visit him; and when he dies follow his funeral.” Related by Muslim.
Bulugh al-Maram 1635, Book 16, The Comprehensive Book, Hadith 1. 1 min read