Narrated Ayyub: Umar bin Abd al-Aziz wrote (a letter) to the people of Basrah: It has reached us from the Messenger of Allah ﷺ, like the tradition narrated by Ibn Umar from the Prophet ﷺ. This version adds: The best calculation is that when we sight the moon of Sha'ban on such-and-such date, fasting will being on such-and-such dates, Allah willing, except they they sight the moon before that (date).