Islam and its Influence on the Lives of Its Adherents - an award-winning work from 1882. The most important textual foundation of Islam is the Quran, which is considered the revealed word of God to the Prophet Muhammad. The second foundation consists of the reports (Hadith) regarding the behavior (Sunna) of Muhammad, who serves as a role model for all Muslims as the Messenger of God. The norms derived from these texts are collectively referred to as Sharia. A proper definition of Islam is not found in the Quran but only in the reports about the Prophet, specifically in the so-called Gabriel Hadith, which is traced back to the Prophet through Umar ibn al-Khattab. Here, a distinction is also made between Islam and faith. A third category introduced is good deeds (ihsan). According to this Hadith, Islam consists of your confession.