We were with Abu Hurairah at his home when he related to us that the Messenger of Allah ﷺ prohibited fasting on the day of Arafah while at Arafah.
حدثنا سليمان بن حرب حدثنا حوشب بن عقيل عن مهدي الهجري
كنا عند أبي هريرة في بيته فحدثنا أن رسول الله ﷺ نهى عن صوم يوم عرفة بعرفة
[Its isnad is hasan]. Ibn Majah narrated it in the Book of Fasting, Chapter on Fasting the Day of Arafah, no. 1732, from the hadith of Hawshab bin Aqeel, and Ibn Khuzayma graded it sahih, no. 2101, as did Hakim, 1/434. I have not seen any valid argument for those who declared it daif.