The Messenger of Allah ﷺ said to us on the day of Ashura, "Has any of you eaten today?"We replied, "Some of us have eaten and some have not."He said, "Then complete the rest of your day, both those who have eaten and those who have not. And send word to the people of the outlying areas to complete the rest of their day as well." By "the people of the outlying areas" he meant those living around Madinah.
حدثنا أبو بكر بن أبي شيبة حدثنا محمد بن فضيل عن حصين عن الشعبي
قال لنا رسول الله ﷺ يوم عاشوراء منكم أحد طعم اليوم قلنا منا طعم ومنا من لم يطعم قال فأتموا بقية يومكم من كان طعم ومن لم يطعم فأرسلوا إلى أهل العروض فليتموا بقية يومهم قال يعني أهل العروض حول المدينة
Its chain is sahih. Nasai reported it in 4/192, Fasting, "If the menstruating woman becomes pure or the traveler arrives during Ramadan, should he fast the rest of his day," no. 2322, and Ahmad in 4/388, from the hadith of Husayn, in the same wording, and Busiri graded it sahih.