Oneness, Uniqueness of Allah (Tawheed)

Bukhari :: Book 9 :: Volume 93 :: Hadith 577

Narrated Abu Huraira:

Allah's Apostle said, "If Allah loves a person, He calls Gabriel, saying, 'Allah loves so and so, O Gabriel love him' So Gabriel would love him and then would make an announcement in the Heavens: 'Allah has loved so and-so therefore you should love him also.' So all the dwellers of the Heavens would love him, and then he is granted the pleasure of the people on the earth." (See Hadith No. 66, Vol. 8)