The first revelation of the Quran occurred on 17th Ramadan (though some scholars say it was on the 27th night which is Laylat al-Qadr) in 610 CE when the Prophet (PBUH) was 40 years old. The first five verses of Surah Al-Alaq were revealed in the Cave of Hira by Angel Jibreel (AS): 'Read in the name of your Lord who created...' This marked the beginning of 23 years of revelation and the Prophet's mission to guide humanity.