Answer and Explanation
Muhammad became the prophet of Islam after he Heard the voice of the Archangel Gabriel calling him .This time he was at the age of 40 years while he engaged in a meditative retreat. And at this time is when he recieved his first revelation from this Angel Gabriel. This revelation is known as Quran and this revelation continued for twenty three years. It is then after getting tat revelation that Muhammad began reciting the words which he heard from God through Archangel Gabriel and he started preaching the truth which God had revealed to him.
Khadija encouraged him to accept the call. She became the first convert to the faith called Islam
