Rights of a Muslim upon a Muslim

Abu Hurairah (May Allah be pleased with him) reported: Messenger of Allah (PBUH) said,
"A believer owes another believer five rights: responding to greetings, visiting him in illness, following his funeral, accepting his invitation, and saying `Yarhamuk-Allah (May Allah have mercy on you),' when he says `Al-hamdu lillah (Praise be to Allah)' after sneezing". [Al-Bukhari and Muslim].
Muslim's narration is,
"There are six rights of a Muslim upon a Muslim: When you meet him, greet him; when he invites you, respond to him; when he seeks counsel, give him advice; when he sneezes and praises Allah, say to him: `May Allah have mercy on you (Yarhamuk-Allah)'; when he is sick, visit him; and when he dies, follow his funeral".

Commentary: The bond of brotherhood among the Muslims has been further strengthened by the list in this Hadith about the rights of Muslims on one another. [Riyad-us-Saliheen: Chapter 27, Reverance towards the Sanctity of the Muslims - Number 238]