Oneness, Uniqueness of Allah (Tawheed)
Bukhari :: Book 9 :: Volume 93 :: Hadith 491
Narrated Juhaifa:
When the Prophet went to bed, he used to say, "Allhumma bismika ahya wa amut." And when he got Up in the mornings he used to say, "Alhamdu lillahi al-ladhi ahyana ba'da ma amatana wa ilaihi-n-nushur."