A Muslim has six rights on another Muslim

Prophet Muhammad ﷺ said:
"A Muslim has six rights on another Muslim. 
1. When you meet him, greet him with salaam.
2. When he invites you, accept the invitation.
3. When he seeks counselling from you advise him. 
4. When he sneezes and says Alhamdulillah (All praises be to Allah), reply with Yarhamkumullah (May Allah have mercy on you). 
5. When he falls ill, visit him. 
6. When he dies, attend his funeral."
[Sahih Muslim]