Bukhari Volume 5, Book 58, Number 182:
Abu Bakr had a slave who used to give him some of his earnings. Abu Bakr used to eat from it. One day he brought something and Abu Bakr ate from it. The slave said to him, "Do you know what this is?" Abu Bakr then enquired, "What is it?" The slave said, "Once, in the pre-Islamic period of ignorance I foretold somebody's future though I did not know this knowledge of foretelling but I, cheated him, and when he met me, he gave me something for that service, and that is what you have eaten from." Then Abu Bakr put his hand in his mouth and vomited whatever was present in his stomach.
Abu Bakr was the first Caliph. He owned a slave who gave him something to eat, which he earned during the Pre-islamic period. The slave earned it by cheating someone. He fed it toAbu Bakr, and Bakr threw up once he knew what it was.
Why would the slave give his master, Abu Bakr, something several years old to eat, especially if he were a Muslim, and Abu Bakr was one of Mohammad's closest companions? Was it because he truly respected Abu Bakr, or was it that he was playing a joke on Abu Bakr? (Thus being like Allah a great trickster (Surah 3:54)
Why did Aisha tell people this? Was it to make fun of her own father, ABbu Bakr, who gave her to Mohammad at age 6?
Did Bukhari include this as part of the Muslim Sunah so that it could be an example to all slaves to permit giving their masters anything that is not clean?
Finally, one must wonder, was the person who was cheated out of the item which Abu Bakr spat out, the same person who asked Mohammad how to deal with people who cheat him during bargain? http://muslimhadith.blogspot.com/2008/05/when-you-bargain-say-no-cheating.html