Islam encourages its ummah to always maintain two relationships, namely 'Hablum MinaAllah' or relationship with Allah and 'Hablum Minalnas', relationship with man. Maintaining relationship with Allah Subhanahu Wata'ala is to worship and obey His commands and stay away from His prohibitions. Meanwhile, maintaining relationship with man means carrying out obligations and fulfilling the rights of fellow Muslims. Among the rights of a Muslim over another Muslim is giving salam. The Friday Sermon touched on the virtues of Giving Salam.
According to the Imam or Prayer Leader, giving Salam is a noble practice and highly encouraged in Islam. A Salam is an address to a fellow Muslim, whether we know them well or otherwise, when commencing a conversation or ending it. Giving salam is sunnah and answering it is wajib or obligatory. Although spreading Salam is highly enjoined, there are also places and times when we are forbidden to say it.
Source: Radio Television Brunei