The Qur'an is the final revelation from God to mankind, revealed to the Prophet Muhammad over 23 years. It is comprised of 114 chapters of varying lengths, divided between those revealed in Mecca focusing on tawhid (monotheism) and the signs of God, and those revealed in Medina providing legislation for worship and social transactions. The Qur'an contains the original, unaltered message from God, delivered by the angel Gabriel to Muhammad, who memorized and recited it to his followers. It is one of the fundamental sources of Islamic teachings.