Fatimah (a.s.) passed away while being angry with Abu Bakr and Umar because they had deprived her of the inheritance left for her by her father, the Prophet (a.s.). Relying on the authority of `A'ishah, al-Bukhari quotes the latter as saying, "... Fatimah (a.s.) daughter of the Messenger of Allah (a.s.) was to receive the inheritance left for her from the fay' [property gained as a peace offering from a hostile party] which Allah had bestowed upon His Messenger (a.s.). Abu Bakr said to her, 'The Messenger of Allah (a.s.) had said, 'We [prophets] leave no inheritance; what we leave behind is charity;' therefore, Fatimah (a.s.) daughter of the Messenger of Allah (a.s.) became angry. She dissociated herself from Abu Bakr until she died. She lived for only six months after the death of the Messenger of Allah (a.s.)." `A'ishah adds saying, "And Fatimah (a.s.) demanded that Abu Bakr give her the share to which she was entitled of the inheritance of the Messenger of Allah (a.s.) from Khaybar, namely Fadak, and the Madinah charity, but Abu Bakr refused saying, 'I shall not leave out anything which the Messenger of Allah (a.s.) used to do.'"[1]
[1] Al-Bukhari, Sahih, Vol. 4, p. 208, in the book of khums in a chapter about obligations.
Her anger with Abu Bakr and Umar was so great that it prompted her to go as far as leaving a will with `Ali (a.s.) that Abu Bakr should not perform the funeral prayers for her after her demise, nor to even walk behind her coffin. Imam `Ali (a.s.) buried her pure body secretly at night as al-Bukhari states in his Sahih, relying on `A'ishah who said, "... Abu Bakr refused that anything should be paid to Fatimah (a.s.). Fatimah (a.s.), therefore, was extremely angry with him, so much so that she dissociated herself from him and never spoke to him until she died. She lived after the demise of the Prophet (a.s.) for six months. When she died, her husband buried her at night. Abu Bakr never called the adhan [to announce her death], nor did he perform the funeral prayers for her."[2]