Hadiths 1.40, 1.41 & 1.42

1.40:
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."
1.41:
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 overtaxing
yourself) as Allah does not get tired (of giving rewards) but
(surely) you will get tired; the best deed (act of Worship) in
the sight of Allah is that which is done regularly."
1.42:
Narrated Anas:
The Prophet said, "Whoever said "None has the right to be
worshipped but Allah and has in his heart good (faith) equal
to the weight of a barley grain will be taken out of Hell. And
whoever said: "None has the right to be worshipped but Allah
and has in his heart good (faith) equal to the weight of a
wheat grain will be taken out of Hell. And whoever said, "None
has the right to be worshipped but Allah and has in his heart
good (faith) equal to the weight of an atom will be taken out
of Hell."