Sahih al-Bukhari 1960
صحيح البخاري#1960Sahihحَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا بِشْرُ بْنُ الْمُفَضَّلِ، حَدَّثَنَا خَالِدُ بْنُ ذَكْوَانَ، عَنِ الرُّبَيِّعِ بِنْتِ مُعَوِّذٍ، قَالَتْ أَرْسَلَ النَّبِيُّ صلى الله عليه وسلم غَدَاةَ عَاشُورَاءَ إِلَى قُرَى الأَنْصَارِ " مَنْ أَصْبَحَ مُفْطِرًا فَلْيُتِمَّ بَقِيَّةَ يَوْمِهِ، وَمَنْ أَصْبَحَ صَائِمًا فَلْيَصُمْ ". قَالَتْ فَكُنَّا نَصُومُهُ بَعْدُ، وَنُصَوِّمُ صِبْيَانَنَا، وَنَجْعَلُ لَهُمُ اللُّعْبَةَ مِنَ الْعِهْنِ، فَإِذَا بَكَى أَحَدُهُمْ عَلَى الطَّعَامِ أَعْطَيْنَاهُ ذَاكَ، حَتَّى يَكُونَ عِنْدَ الإِفْطَارِ.
Narrated Ar-Rubai' bint Mu'awwidh:"The Prophet (ﷺ) sent a messenger to the village of the Ansar in the morning of the day of 'Ashura' (10th of Muharram) to announce: 'Whoever has eaten something should not eat but complete the fast, and whoever is observing the fast should complete it.' "She further said, "Since then we used to fast on that day regularly and also make our boys fast. We used to make toys of wool for the boys and if anyone of them cried for food, he was given those toys till it was the time of the breaking of the fast
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 30:67