Al-Matalib al-'Aliyah 1237 — Standing at Arafah and departing from it

It is narrated from Abd al-Aziz bin Abdullah bin Khalid bin Asid that the Messenger of Allah (peace and blessings be upon him) said: "Arafah (the valid day of Arafah) is the day on which all the people together recognise it (in the plain of Arafat)."
The Imams of hadith say in explaining it that the purpose of this prophetic statement is to make clear that days such as the Day of Arafah, Eid al-Adha and Eid al-Fitr do not depend merely on individual opinion, but on the community of the Muslims, their mutual agreement and the gathering of the great majority. Therefore, the day on which the Muslim Ummah collectively performs these rites is the day that is, in the Shari'ah, called the Day of Arafah.