Sahih al-Bukhari 7265
Sahih al-Bukhari · Book 95: Accepting Information Given by a Truthful Person · The Prophet (saws) used to send commanders and messengers one after another
Narrated Salama bin Al-Akwa`:
حَدَّثَنَا مُسَدَّدٌ ، حَدَّثَنَا يَحْيَى ، عَنْ يَزِيدَ بْنِ أَبِي عُبَيْدٍ ، حَدَّثَنَا سَلَمَةُ بْنُ الأَكْوَعِ ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ لِرَجُلٍ مِنْ أَسْلَمَ " أَذِّنْ فِي قَوْمِكَ ـ أَوْ فِي النَّاسِ ـ يَوْمَ عَاشُورَاءَ أَنَّ مَنْ أَكَلَ فَلْيُتِمَّ بَقِيَّةَ يَوْمِهِ، وَمَنْ لَمْ يَكُنْ أَكَلَ فَلْيَصُمْ " .
Allah's Messenger (ﷺ) said to a man from the tribe of Al-Aslam, "Proclaim among your people (or the people) on the day of 'Ashura' (tenth of Muharram), 'Whosoever has eaten anything should fast for the rest of the day; and whoever has not eaten anything, should complete his fast.' "