Whose advice led to the commencement of the Hijri year from the month of Muharram (محرم)?

The advice that led to the commencement of the Hijri year from the month of Muharram (محرم) is attributed to Umar ibn al-Khattab, the second caliph of Islam. The Islamic calendar, also known as the Hijri calendar, began during his caliphate in 638 CE.

Umar sought to establish a systematic way to track time and events and consulted his companions about the best way to do so. They collectively decided to begin the Islamic calendar based on the migration (Hijrah) of the Prophet Muhammad (peace be upon him) from Mecca to Medina, which was a significant turning point in Islamic history.

Muharram was chosen as the first month of the Hijri year because it is one of the four sacred months in Islam, thus underscoring its importance and ensuring respect for its sanctity. This decision has facilitated the organization of events and religious observances in the Muslim community over the centuries.