Silsilat al-Ahadith al-Sahihah

The Messenger of Allah (peace and blessings be upon him) said: "On this day of Ashura, announce among your people or among the people that whoever has eaten should observe fasting for the rest of the day, and whoever has not eaten should fast for the whole day." This hadith is narrated from Salamah bin Akwa’, Rabi’ bint Mu’awwidh, Muhammad bin Saifi, Hind bint Asma, Abu Hurairah, and Abdullah bin Abbas (may Allah be pleased with them), from some unspecified individuals of the Aslam tribe, from Ma’bad Qurashi, and is also narrated mursal from Muhammad bin Sirin.