The rights of a Muslim over another Muslim are six

Abu Huraira reported: The Messenger of Allah, peace and blessings be upon him, said, “The rights of a Muslim over another Muslim are six.” It was said, “What are they, O Messenger of Allah?” He said, “When you meet him, you greet him with peace; and when he invites you, you respond; and when he seeks your advice, you council him; and when he sneezes and praises Allah, you respond to him; and when he becomes ill, you visit him; and when he dies, you follow his funeral prayer.”

Source: Sahih Muslim 2162

Grade: Sahih (authentic) according to Imam Muslim

عَنْ أَبِي هُرَيْرَةَ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ 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 فَسَمِّتْهُ وَإِذَا مَرِضَ فَعُدْهُ وَإِذَا مَاتَ فَاتَّبِعْهُ

2162 صحيح مسلم كِتَاب السَّلَامِ خمس تجب للمسلم على أخيه