Sahih Muslim
The Book of Faith (Kitab Al-Iman)
Book Number: 001 / Hadith Number: 76
It is reported on the authority of Abu Huraira that the Messenger of Allah (may peace and blessings be upon him) observed: He who believes in Allah and the Last Day does not harm is neighbour, and he who believes in Allah and the Last Day shows hospitality to his guest and he who believes in Allah and the Last Day speaks good or remains silent.