Sahih Al Bukhari – Book of Good Manners And Form (Al-Adab)

Volumn 008, Book 073, Hadith Number 047.
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Narated By Abu Huraira : Allah's Apostle said, 

1- "Anybody who believes in Allah and the Last Day should not harm his neighbor, and 

2- anybody who believes in Allah and the Last Day should entertain his guest generously and 

3- anybody who believes in Allah and the Last Day should talk what is good or keep quiet. (i.e. abstain from all kinds of evil and dirty talk).