"Signs of a hypocrite are three: whenever he speaks he lies; whenever he promises, he breaks his promises; and whenever he has been entrusted, he betrays his trust; even if he fasts and prays and even if he claims he is a Muslim." [Bukhari & Muslim]

And in another narration in the book of Imam Bukhari on the authority of Abdullah Ibn Umar:

“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."