While praying one night in 610 on Mount Hira, Mohammed had a revelation that changed not only his life but also world history. He heard a divine voice, believed to be the angel Gabriel, speak to him. The angel said, “Read!” referring to the words of God. Gabriel explained to Mohammed that God is God, there is no other God; therefore God is called Allah, meaning “the one who is God.” Mohammed learned that he was the last and greatest prophet and that he should proclaim the word of God: “la ilaha illa ‘Llah!”; “There is no god but God!” The voice of Gabriel would continue to dictate the word of Allah through Mohammed, the “Messenger of God.”
After that night, referred to as the Night of Power, Mohammed preached to the polytheistic people of Mecca, hoping to convert them to monotheism, but his religious news was not well received. The tribes of Mecca believed it was an insult to their ancestors and a threat to future generations to end the old traditions and adapt to a new religion based solely on the words of one man born in their time.
By 622, persecution forced Mohammed and a small group of disciples (made up of his close friends, relatives, and his wife) out of Mecca. They traveled 250 miles of desert to the town of Yathrib in the north, later named Medina an-Nabi, or “the city of the Prophet.” The people of Yathrib welcomed Mohammed and his followers based on his good reputation. They did not force Islam upon the people; rather, most of them naturally came to believe in what Mohammed had to teach them. They trusted that he had heard the words of God. This migration of 622 is called the Hijra, and it marks the beginning of the Muslim era.