From Sahih Muslim (Hadith 48):
It is narrated on the authority of Abu Shuraih al-Khuzai' that the Prophet (may peace and blessings of Allah be upon him) observed: He who believes in Allah and the Last Day should do good to his neighbour and he who believes in Allah and the Last Day should show hospitality to the guest and he who believes in Allah and the Last Day should either speak good or better remain silent.
Reference: Muslim 48