Musannaf Ibn Abi Shaybah

Hazrat Abu Umair bin Anas says that my uncle, an Ansari, narrated to me that once we did not see the Shawwal moon at night and so we fasted the next day. In the latter part of the day, some horsemen came and testified before the Prophet (peace and blessings be upon him) that they had seen the moon yesterday. The Prophet ordered the people to break their fast and said that tomorrow the people should come to the Eidgah for the Eid prayer.