Oneness, Uniqueness of Allah (Tawheed)
Bukhari :: Book 9 :: Volume 93 :: Hadith 552
Narrated Muawiya:
I heard the Prophet saying, "A group of my followers will keep on following Allah's Laws strictly and they will not be harmed by those who will disbelieve them or stand against them till Allah's Order (The Hour) will come while they will be in that state."