Sahih Bukhari Volume 8, Book 73, Hadith Number 48.

Narated By Abu Shuraih Al-Adawi : My ears heard and my eyes saw the Prophet when he spoke, “Anybody who believes in Allah and the Last Day, should serve his neighbor generously, and anybody who believes in Allah and the Last Day should serve his guest generously by giving him his reward.” It was asked. “What is his reward, O Allah’s Apostle?” He said, “(To be entertained generously) for a day and a night with high quality of food and the guest has the right to be entertained for three days (with ordinary food) and if he stays longer, what he will be provided with will be regarded as Sadaqa (a charitable gift). And anybody who believes in Allah and the Last Day should talk what is good or keep quite (i.e. abstain from all kinds of dirty and evil talks).”