Musnad Ahmad 32:2030

Abdullah narrated to us, Yaqub ibn Ibrahim al-Dawraqi narrated to us, he said: Sa'id ibn Amir narrated to me, from Shu'bah, from Qatadah, from Anas: "That paternal uncles of his testified before the Prophet, peace and blessings of Allah be upon him, regarding the sighting of the crescent moon. So he commanded the people to break their fast and to go out to their Eid the next morning."