Musannaf Ibn Abi Shaybah 9614 — Fasting the day of Ashura

Abu Bakr bin Abd al-Rahman bin al-Harith said: On the evening of the night of Ashura, Sayyiduna Umar (may Allah be pleased with him) sent a message to Abd al-Rahman bin al-Harith, saying: "Eat suhur and begin the morning fasting." So Abd al-Rahman began the morning fasting.