Sayyiduna Ali (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) used to fast on the day of Ashura and used to command it as well.
Abdullah bin Ahmad and al-Bazzar recorded it. Its chain contains a narrator, Jabir al-Ju'fi, whom Shu'bah and al-Thawri declared thiqah (trustworthy), and a great deal has been said about him.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصيام / 5107