Sahih al-Bukhari 6135
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).
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ يُوسُفَ، أَخْبَرَنَا مَالِكٌ، عَنْ سَعِيدِ بْنِ أَبِي سَعِيدٍ الْمَقْبُرِيِّ، عَنْ أَبِي شُرَيْحٍ الْكَعْبِيِّ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ مَنْ كَانَ يُؤْمِنُ بِاللَّهِ وَالْيَوْمِ الآخِرِ فَلْيُكْرِمْ ضَيْفَهُ، جَائِزَتُهُ يَوْمٌ وَلَيْلَةٌ، وَالضِّيَافَةُ ثَلاَثَةُ أَيَّامٍ، فَمَا بَعْدَ ذَلِكَ فَهْوَ صَدَقَةٌ، وَلاَ يَحِلُّ لَهُ أَنْ يَثْوِيَ عِنْدَهُ حَتَّى يُحْرِجَهُ ‏"‏‏.‏ حَدَّثَنَا إِسْمَاعِيلُ، قَالَ حَدَّثَنِي مَالِكٌ، مِثْلَهُ وَزَادَ ‏"‏ مَنْ كَانَ يُؤْمِنُ بِاللَّهِ وَالْيَوْمِ الآخِرِ فَلْيَقُلْ خَيْرًا أَوْ لِيَصْمُتْ ‏"‏‏.‏