Narrated AbuUmayr ibn Anas:

AbuUmayr reported on the authority of some of his paternal uncles who were Companions of the Prophet (ﷺ): Some men came riding to the Prophet (ﷺ) and testified that they had sighted the new moon the previous day. He (the Prophet), therefore, commanded the people to break the fast and to go out to their place of prayer in the morning.

حَدَّثَنَا حَفْصُ بْنُ عُمَرَ، حَدَّثَنَا شُعْبَةُ، عَنْ جَعْفَرِ بْنِ أَبِي وَحْشِيَّةَ، عَنْ أَبِي عُمَيْرِ بْنِ أَنَسٍ، عَنْ عُمُومَةٍ، لَهُ مِنْ أَصْحَابِ النَّبِيِّ صلى الله عليه وسلم أَنَّ رَكْبًا جَاءُوا إِلَى النَّبِيِّ صلى الله عليه وسلم يَشْهَدُونَ أَنَّهُمْ رَأَوُا الْهِلاَلَ بِالأَمْسِ فَأَمَرَهُمْ أَنْ يُفْطِرُوا وَإِذَا أَصْبَحُوا أَنْ يَغْدُوا إِلَى مُصَلاَّهُمْ ‏.‏