Oneness, Uniqueness of Allah (Tawheed)
Bukhari :: Book 9 :: Volume 93 :: Hadith 575
Narrated Abu Said Al-Khudri:
The Prophet said, "Allah will say (on the Day of Resurrection), 'O Adam!' Adam will reply, 'Labbaik wa Sa'daik! ' Then a loud Voice will be heard (Saying) 'Allah Commands you to take out the mission of the Hell Fire from your offspring.' "