The document describes the history surrounding the succession of leadership following the death of the Prophet Muhammad. It tells of the divisions that emerged between those who supported Abu Bakr and those who believed Ali bin Abi Talib should have led as he was appointed by the Prophet. Over time different groups formed, including the Sunnis who followed the elected caliphs, and the Shias who believed in the divine authority of the Imams descended from Ali and Fatima. The letter aims to promote unity among Muslims and a return to the original message of the Prophet.