Oneness, Uniqueness of Allah (Tawheed)
Bukhari :: Book 9 :: Volume 93 :: Hadith 529
Narrated Jarir:
We were sitting with the Prophet and he looked at the moon on the night of the full-moon and said, "You people will see your Lord as you see this full moon, and you will have no trouble in seeing Him, so if you can avoid missing (through sleep or business, etc.) a prayer before sunrise (Fajr) and a prayer before sunset (Asr) you must do so." (See Hadith No. 529, Vol. 1)