In what order should hair trimming or shaving commence?
Chapter on Mentioning Hajj and Entering Makkah
Al-Mughni
Book of Hajj
Primary text
It is recommended to begin with the right side (Al-Shaqq Al-Ayman). This is based on the narration of Anas that the Messenger of Allah, peace be upon him, instructed the barber, 'Take,' gesturing towards his right side first, then the left. Furthermore, the Prophet, peace be upon him, favored beginning with the right in all his affairs.
Supporting text
Imam Ahmad specified that one must begin with the right side until the two eminences (the prominence of the skull) are surpassed.