Musannaf Ibn Abi Shayba 35:135

Hushaym narrated to us, from Abu Bishr, from Abu Umayr ibn Anas, who said: My paternal uncles from the Ansar, from the companions of the Prophet (may Allah bless him and grant him peace), narrated to me. They said: The crescent of Shawwal was obscured from us, so we woke up fasting. Then a caravan arrived at the end of the day and they testified before the Prophet (may Allah bless him and grant him peace) that they had seen the crescent yesterday. So the Prophet (may Allah bless him and grant him peace) ordered them to break their fast and to go out to their Eid the next day. And it was mentioned that Abu Hanifa said: They do not go out the next day.