Sahih Muslim | Book 26 | Hadith Number 5379
Narrated by Abu Huraira
Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: Six are the rights of a Muslim over another Muslim. It was said to him: Allah's Messenger, what are these? Thereupon he said: When you meet him, offer him greetings; when he invites you to a feast accept it, when he seeks your council give him, and when he sneezes and says: "All praise is due to Allah," you say Yarhamuk Allah (may Allah show mercy to you); and when he fails ill visit him; and when he dies follow his bier.