سنن أبي داود

Narrated Kuraib: That Umm al-Fadl, daughter of al-Harith, sent him to Mu'aqiyah in Syria. He said: I came to syria and performed her work. The moon of Ramadan appeared while I was in Syria. We sighted the moon on the night of Friday. When I came to Median towards the end of the month (of Ramadan), Ibn 'Abbas asked me about the moon. He said: When did you sight the moon ? I said: I sighted it on the night of Friday. He asked: Did you sight it yourself ? I said: Yes, and the people sighted it. They fasted and Mu'awiyah also fasted. He said: But we sighted it on the night of saturday. Since then we have been fasting until we complete thirty days or we sight it. Then I said: Are the sighting of the moon by Mu'awiyah and his fasts not sufficient for us? He replied: No. The Messenger of Allah (ﷺ) commanded us to do so.