Musnad Ahmad 25:220

Waki’ narrated to us, from Isra’il—or someone else—from Jabir, from ‘Ikrimah, from Ibn ‘Abbas, who said: "The Messenger of Allah (ﷺ) sent [a messenger] to the people of a village at a distance of four farsakhs—or he said: two farsakhs—on the day of ‘Ashura. He ordered whoever had eaten to not eat for the remainder of his day, and whoever had not eaten to complete his fast."