Muhammad [s], though endeared and respected by Makkans for his wisdom and virtues, preferred solitude and kept his distance from the polytheist society. Disgusted with the corruption all around, he used to retire to the Cave of Hira, in a mountain a few kilometres from Makkah, meditating Allah's Majesty and worshipping Him. Initially he used to remain in the cave for a day or two and sometimes even 10 nights or more but the next few years saw him spending a whole month in that cave, praying to Allah and contemplating guidance for the deviated people.
Finally the day dawned which was change the history of the world. When he had reached the age of 40 and was engrossed as usual in praying to Allah at his retreat of cave Hira, suddenly that harbinger of Divine tidings, the Archangel Gabriel, appeared with the first verses of the Holy Qur'an:
"Recite in the name of your Lord Who created. Created man from a clot. Recite and your Lord is most Generous. Who taught (to write) with the pen. Taught man what he knew not."
Holy Qur'an (96:1-5)
With these verses, Gabriel [a] announced to Muhammad [s] that Almighty Allah had formally chosen him to be His last and final Messenger to humankind.
Muhammad's [s] heart was filled with joy, and he thanked Almighty Allah for bestowing this great honour upon him. He hurried to his house to tell his wife Khadija about his appointment to Prophethood.
Khadija on hearing the event at once believed in her husband's Prophethood and so did his young cousin Ali [a]. Consequently Ali and Khadija became the first ever male and female Muslims respectively. Thus started the beginning of a divine mission which was destined not only to cleanse the Arabian Peninsula of the filth of polytheism but whose radiance would eventually dispel darkness from all over the world.
Muhammad's [s] formal announcement of his Prophethood had a mixed reaction on Makkan society. While the oppressed classes hastened towards the call of Islam, happy that the day of deliverance had finally dawned, the Makkan oligarchy and those who felt a danger to their vested interests and hegemony; ganged up to ridicule the Prophet, in their desperate bid to nip in the bud the final revelation to the human race.
Undeterred by Jahiliyah's arrogant attempts, Muhammad [s] continued to propagate the great divine mission entrusted to him, and the next 23 years of his lifetime saw the gradual unfolding of the grand miraculous event; the Holy Qur'an, Allah's own words sent down through the Archangel Gabriel.
 Even today after 14 centuries, Allah's book the Holy Qur'an stands as a living miracle for humanity. Its revelation was completed a couple of months before the Messenger's passing away, and besides containing the 'Shariah' (canonical laws) for the Muslims, it is a source of knowledge goading man to contemplate and discover the mysteries of science, inspiring high ethical values and morals in its readers and showing the perfect path for mankind's happiness both in this world and the hereafter.