SAHIH BUKHARI

Volume 1, Book 2, Number 32:

Narrated Abu Huraira:

The Prophet said, "The signs of a hypocrite are three: 1. Whenever he speaks, he tells a lie.

2. Whenever he promises, he always breaks it (his promise ).

3. If you trust him, he proves to be dishonest. (If you keep something as a trust with him, he will not return it.)"