صحيح البخاري

Narrated Abu Shuraih Al-Ka`bi:

Allah's Messenger (ﷺ) said, Whoever believes in Allah and the Last Day, should serve his guest generously. The guest's reward is: To provide him with a superior type of food for a night and a day and a guest is to be entertained with food for three days, and whatever is offered beyond that, is regarded as something given in charity. And it is not lawful for a guest to stay with his host for such a long period so as to put him in a critical position."

Narrated Malik:

Similarly as above (156) adding, "Who believes in Allah and the Last Day should talk what is good or keep quiet." (i.e. abstain from dirty and evil talk, and should think before uttering).