At the age of forty, Muhammad received his first revelation from God through the Angel Gabriel. The revelations continued for twenty-three years, and they are collectively known as the Quran.
As soon as he began to recite the Quran and to preach the truth which God had revealed to him, he and his small group of followers suffered persecution from unbelievers. The persecution grew so fierce that in the year 622 God gave them the command to emigrate. This emigration from Makkah to the city of Madinah, some 260 miles to the north, marks the beginning of the Muslim calendar.
After several years, Muhammad and his followers were able to return to Makkah, where they forgave their enemies. Before Muhammad died, at the age of sixty-three, the greater part of the Arabian Peninsula had become Muslim, and within a century of his death, Islam had spread to Spain in the West and as far East as China. Among the reasons for the rapid and peaceful spread of Islam was the truth and clarity of its doctrine. Islam calls for faith in only one God, Who is the only one worthy of worship.
The Prophet Muhammad was a perfect example of an honest, just, merciful, compassionate, truthful, and brave human being. Though he was a man, he was far removed from all evil characteristics and strove solely for the sake of God and His reward in the Hereafter. Moreover, in all his actions and dealings, he was ever mindful and fearful of God.