Hadithcore
Sunan an-Nasa'i, 1557
sahih· Darussalam

It was narrated from 'Umair bin Anas from his paternal uncles, that :

Some people saw the crescent moon and came to the Prophet (ﷺ), and he told them to break their fast after the sun has risen and to go out for 'Eid the (morning of the) following day.

أَخْبَرَنَا عَمْرُو بْنُ عَلِيٍّ، قَالَ حَدَّثَنَا يَحْيَى، قَالَ حَدَّثَنَا شُعْبَةُ، قَالَ حَدَّثَنَا أَبُو بِشْرٍ، عَنْ أَبِي عُمَيْرِ بْنِ أَنَسٍ، عَنْ عُمُومَةٍ، لَهُ أَنَّ قَوْمًا، رَأَوُا الْهِلاَلَ فَأَتَوُا النَّبِيَّ صلى الله عليه وسلم فَأَمَرَهُمْ أَنْ يُفْطِرُوا بَعْدَ مَا ارْتَفَعَ النَّهَارُ وَأَنْ يَخْرُجُوا إِلَى الْعِيدِ مِنَ الْغَدِ ‏.‏

References2 variants
In-Book Reference
Book 19, Hadith 2
English Reference
Vol. 2, Book 19, Hadith 1558