When did the Qur'an descend upon our master Muhammad?

The majority of scholars hold that the first part of the Quran revealed to the Prophet, peace and blessings be upon him, was the beginning of Surat Al-Alaq: "Recite in the name of your Lord who created; Created man from a clinging substance. Recite, and your Lord is the Most Generous; Who taught by the pen; Taught man that which he knew not." This occurred on the seventeenth or twenty-fourth of Ramadan.

Scholars differed regarding the age of the Prophet, peace and blessings be upon him, when the revelation began. Some said he was forty years old, based on a hadith from Ibn Abbas, while others said forty-three years, based on another narration from Ibn Abbas.