Hadith about belief.

Bukhari :: Book 1 :: Volume 2 :: Hadith 21

Narrated Abu Said Al-Khudri:

The Prophet said, "When the people of Paradise will enter Paradise and the people of Hell will go to Hell, Allah will order those who have had faith equal to the weight of a grain of mustard seed to be taken out from Hell. So they will be taken out but (by then) they will be blackened (charred). Then they will be put in the river of Haya' (rain) or Hayat (life) (the Narrator is in doubt as to which is the right term), and they will revive like a grain that grows near the bank of a flood channel. Don't you see that it comes out yellow and twisted"

Bukhari :: Book 1 :: Volume 2 :: Hadith 22

Narrated Abu Said Al-Khudri:

Allah's Apostle said, "While I was sleeping I saw (in a dream) some people wearing shirts of which some were reaching up to the breasts only while others were even shorter than that. Umar bin Al-Khattab was shown wearing a shirt that he was dragging." The people asked, "How did you interpret it? (What is its interpretation) O Allah's Apostle?" He (the Prophet ) replied, "It is the Religion."

Bukhari :: Book 1 :: Volume 2 :: Hadith 23

Narrated 'Abdullah (bin 'Umar):

Once Allah's Apostle passed by an Ansari (man) who was admonishing to his brother regarding Haya'. On that Allah's Apostle said, "Leave him as Haya' is a part of faith." (See Hadith No. 8)