The Prophet said: "There are four (traits), whoever has them is a hypocrite and whoever has one of them, then has one of the traits of hypocrisy, until he gives it up: When he speaks, he lies; when he makes a promise, he breaks it; when he makes a covenant, he betrays it; and when he argues, he resorts to foul language."
Sunan an-Nasa'i Book 47, Hadith 36