Oneness, Uniqueness of Allah (Tawheed)
Bukhari :: Book 9 :: Volume 93 :: Hadith 561
Narrated Abu Huraira:
Allah's Prophet Solomon who had sixty wives, once said, "Tonight I will have sexual relation (sleep) with all my wives so that each of them will become pregnant and bring forth (a boy who will grow into) a cavalier and will fight in Allah's Cause." So he slept with his wives and none of them (conceived and) delivered (a child) except one who brought a half (body) boy (deformed). Allah's Prophet said, "If Solomon had said; 'If Allah Will,' then each of those women would have delivered a (would-be) cavalier to fight in Allah's Cause." (See Hadith No. 74 A, Vol. 4).