Iman is an expression of the truth a Muslim recognizes, defined by the Prophet: “Faith is knowledge in the heart, a voicing with the tongue, and an activity with the limbs.” The six principles of Iman are mentioned in the Hadith by Gabriel: God, the angels, the scriptures, the prophets, the Last Day and the measuring out. Although there are six principles, they have been grouped by philosophers into three main roots: the tawid, prophecy and the Return. The tawid is the divine unity, the universal message brought by individual prophets to a particular people, at a particular time and place in a particular manner.