Narrated 'Aisha:

Once the Prophet came while a woman was sitting with me. He said, "Who is she?" I replied, "She is so and so," and told him about her (excessive) praying. He said disapprovingly, "Do (good) deeds which is within your capacity (without being overtaxed) as Allah does not get tired (of giving rewards) but (surely) you will get tired and the best deed (act of Worship) in the sight of Allah is that which is done regularly."

Narrated 'Abdullah bin 'Amr:

The Prophet said, "Whoever has the following four (characteristics) will be a pure hypocrite and whoever has one of the following four characteristics will have one characteristic of hypocrisy unless and until he gives it up.

1. Whenever he is entrusted, he betrays.

2. Whenever he speaks, he tells a lie.

3. Whenever he makes a covenant, he proves treacherous.

4. Whenever he quarrels, he behaves in a very imprudent, evil and insulting manner."