It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) commanded us to fast on the day of Ashura, while previously the Jews used to fast on this day.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 14663
Hadith Gradingحکم دارالسلام:صحيح لغيره، وهذا إسناد ضعيف لسوء حفظ ابن لهيعة