When Abu Bakr and Umar both decided to usurp FADAK from Hazrat Zahra (SA) and when she was informed of this news she headed the Masjid al-Nabi (PBUH) (the mosque of the holy prophet) while she was being accompanied by a group of disciples and relatives so as to take her rights and issue an ultimatum demanding her right – the right which was granted to her by the holy prophet when he was alive. At that time some of the immigrants (Muhajirin) and the Ansar were gathered with Abu Bakr in the mosque. When she entered the Mosque of the prophet (PBUH) with her companions, a curtain was set up between her and the people. Then Hazrat Fatima (SA) let out a heart-rending wail and because this wail all the people in the mosque started crying. She let the people to be quiet after a while and then she commence her speech by praising the Almighty Allah and sending peace and blessing upon the Messenger of Allah (pbuh), and by the moment the people heard the name of the Prophet (PBUH), they started crying again.
source : erfan.ir