Does a Muslim sin by not fulfilling one of the rights of a Muslim mentioned in the Hadith of the Messenger of Allah, peace and blessings be upon him about the Muslim’s rights over another Muslim.?

The right of a Muslim upon another Muslim encompasses five matters: returning the greeting (salaam), visiting the sick, following funeral processions, accepting invitations, and saying "Yarhamukallah" (may Allah have mercy on you) to one who sneezes. Another hadith adds a sixth right: offering advice when sought. These rights vary between being an individual obligation (wajib ayni), a collective obligation (wajib kifayi), and a recommended act (mustahabb). Returning the greeting is an individual obligation for a lone person and a collective obligation for a group, while initiating the greeting is a sunnah. Visiting the sick and accompanying funeral processions are collective obligations. Accepting invitations is obligatory for a wedding feast and recommended for other occasions, under certain conditions. Saying "Yarhamukallah" to one who sneezes is obligatory for whoever hears the sneezer praise Allah. Giving advice is a collective obligation, even if not explicitly requested.