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.)"

Volume 1, Book 2, Number 40:

Narrated Abu Huraira:
Allah's Apostle said, "If any one of you improve (follows strictly) his Islamic religion then his good deeds will be rewarded ten times to seven hundred times for each good deed and a bad deed will be recorded as it is."