وعن أبي قتادة رضي الله عنه أن رسول الله صلى الله عليه وسلم سئل عن صيام يوم عاشوراء فقال:
"يكفر السنة الماضية"
Abu Qatadah (May Allah be pleased with him) reported:
The Messenger of Allah (ﷺ) was asked about observing As-Saum (the fast) on the tenth day of Muharram, and he replied, "It is an expiation for the sins of the preceding year."
[Muslim].
Reported by Ahmad (No. 21572). Cited in Riyad as-Salihin (No. 1252).