Bukhari :: Book 4 :: Volume 56 :: Hadith 759
Narrated 'Abdullah bin 'Amr:

The Prophet never used bad language neither a "Fahish nor a Mutafahish. He used to say "The best amongst you are those who have the best manners and character."

Bukhari :: Book 3 :: Volume 43 :: Hadith 639
Narrated 'Abdullah bin 'Amr:

The Prophet said, "Whoever has (the following) four characters will be a hypocrite, and whoever has one of the following four characteristics will have one characteristic of hypocrisy until he gives it up. These are: (1 ) Whenever he talks, he tells a lie; (2) whenever he makes a promise, he breaks it; (3) whenever he makes a covenant he proves treacherous; (4) and whenever he quarrels, he behaves impudently in an evil insulting manner."