Oneness, Uniqueness of Allah (Tawheed)

Bukhari :: Book 9 :: Volume 93 :: Hadith 557

Narrated 'Ali bin Abi Talib:

That one night Allah's Apostle visited him and Fatima, the daughter of Allah's Apostle and said to them, "Won 't you offer (night) prayer?.. 'Ali added: I said, "O Allah's Apostle! Our souls are in the Hand of Allah and when He Wishes to bring us to life, He does." Then Allah's Apostle went away when I said so and he did not give any reply. Then I heard him on leaving while he was striking his thighs, saying, 'But man is, more quarrelsome than anything.' (18.54)