At first, Muhammad divulged his experience only to his wife and his immediate circle. But as more revelations enjoined him to proclaim the oneness of God universally, his following grew, at first among the poor and the slaves, but later also among the most prominent men of Mecca. The revelations he received at this time and those he did so later are all incorporated in the Quran, the Scripture of Islam.
After Muhammad [saw] had preached publicly for more than a decade, the opposition to him reached such a high pitch that, fearful for their safety, he sent some of his adherents to Ethiopia, where the Christian ruler extended protection to them, the memory of which has been cherished by Muslims ever since. But in Mecca, the persecution worsened. Muhammad’s followers were harassed, abused, and even tortured. At last, therefore, Muhammad [saw] sent seventy of his followers off to the northern town of Yathrib, which was later to be renamed Medina (“The City”). Later, in the early fall of 622, he learned of a plot to murder him and, with his closest friend, Abu Bakr al-Siddiq, set off to join the emigrants.