Abu Umayr bin Anas narrates from some of his paternal uncles who were Companions of the Prophet (peace and blessings be upon him) (may Allah be pleased with them) that the people of Madinah began the morning fasting on the last day of Ramadan in the time of the Messenger of Allah (peace and blessings be upon him). Towards the end of the day a caravan arrived and testified before the Messenger of Allah (peace and blessings be upon him) that they had seen the crescent the day before, so the Messenger of Allah (peace and blessings be upon him) commanded the people to break their fast and to go to the Eid prayer-ground the next morning.
This is a hasan (good) chain. Abu Umayr narrated it from paternal uncles of his among the Companions of the Prophet (peace and blessings be upon him), and the Companions of the Prophet (peace and blessings be upon him) are all thiqat (trustworthy), so it makes no difference whether they are named or not.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8196