The Messenger of Allah ﷺ used to fast on Saturday and Sunday more often than on other days, and he would say, "They are festival days for the polytheists, so I love to differ from them."
كان رسول الله ﷺ يصوم يوم السبت الأحد أكثر مما يصوم من الأيام ويقول: إنهما يوما عيد المشركين، فأنا أحب أن أخالفهم.
Narrated by Ahmad (26750), and Tabarani in Al-Kabir (23/283), and Ibn Khuzayma graded it sahih (2167), and Ibn Hibban (3616, 3646), and Hakim (1/436), all of them through various routes from Abdullah bin Mubarak, who said, Abdullah bin Muhammad bin Umar bin Ali informed me, who said, my father narrated to us, from Kurayb the freedman of Ibn Abbas, from Umm Salama, and he related it.Its chain is hasan because of Abdullah bin Muhammad bin Umar bin Ali, who is the son of Abu Talib, and his father Muhammad bin Umar, for both of them are truthful narrators. As for Abdullah bin Muhammad, Ibn Madini said of him, "middling," and Daraqutni deemed him trustworthy, and Ibn Hibban mentioned him among the trustworthy narrators, and many narrators transmitted from him, among them Ibn Mubarak. So Ibn Hajar's statement in Taqrib, "acceptable," is not acceptable, rather his hadith is hasan according to the methodology of the hadith scholars, among them Ibn Hajar himself, and someone of his standing does not need corroboration.