Sahih Bukhari
Belief
Volume: 001 / Book Number: 002 / Hadith Number: 32
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.)"