The Islamic religion is represented by two main directions: Sunni and Shia. Each of the directions has its own legal doctrine, represented by several madhhabs (legal schools). Each of them, in turn, has its own sources of law, in accordance with which religious scholars make their legal decisions. Analyzing the history of the emergence of madhhabs, we can see that their formation was influenced by historical, religious, political, social, economic and other factors. J. Schacht wrote that in the first century of the Hijri (Islamic chronology), many distinctive features of Islamic law emerged, and the emerging Islamic society created its own legal institutions.  At the same time, one should pay attention to the fact that in the early history of the Islamic state and the formation of Islamic law there were events in which we can see the reflection of certain religious and legal ideas, which later formed the basis of differences both between madhhabs and between whole directions of Islamic law. These events took place almost immediately after the death of the Prophet Muhammad and the election of Abu Bakr as Caliph. For the period of his reign, the events of his confrontation with members of Ahl al-Bayt (the progeny of the Prophet) are quite interesting. Firstly, this was expressed in the fact that Ali ibn Abi Talib was not among the first to take the oath of allegiance to Abu Bakr as caliph. This issue was highlighted in the works of Muslim scholars, especially Shia scholars since they consider this event to be one of the first manifestations of Shia ideology. Another such event, we consider the discussion between Fatima and Abu Bakr about the ownership of the lands of Fadak. For a brief description of this event, let us cite a hadith: ‘Narrated Aisha: "Fatima, the daughter of the Prophet, sent someone to Abu Bakr (when he was a caliph), asking for her inheritance of what Allah's Messenger had left of the property bestowed on him by Allah from the Fai (i.e., booty gained without fighting) in Al-Madina, and Fadak, and what remained of the Khumus of the Khaibar booty. On that, Abu Bakr said: "Allah’s Messenger said:  "Our property is not inherited. Whatever we leave, is Sadaqa (charity), but the family of (the Prophet) Muhammad can eat of this property". By Allah, I will not make any change in the state of the Sadaqa of Allah's Messenger and will leave it as it was during the lifetime of Allah's Messenger, and will dispose of it as Allah's Messenger used to do". So, Abu Bakr refused to give anything of that to Fatima’.  
We believe that these two events played a very important role in the manifestation of certain features that later became inherent in the Sunni and Shia, and laid the foundations for the division of the Muslim community (ummah) into two directions, thereby forming certain characteristics for the legal systems of each of them. The purpose of this work is to examine the impact of these two events on the formation of the sources of Sunni and Shia law.