I heard my father narrating from a man, from Ibn Umar, that he was asked about fasting on the Day of Arafah. He said, "We went out with the Messenger of Allah ﷺ and he did not fast it, and with Abu Bakr and he did not fast it, and with Umar and he did not fast it, and with Uthman and he did not fast it. I do not fast it myself, nor do I command you to fast it or forbid you from fasting it. If you wish, fast it, and if you wish, do not fast it."
حدثنا عفان حدثنا شعبة قال
سمعت أبي يحدث عن رجل عن ابن عمر أنه سأله عن صوم يوم عرفة قال خرجنا مع رسول الله ﷺ فلم يصمه ومع أبي بكر فلم يصمه ومع عمر فلم يصمه ومع عثمان فلم يصمه وأنا لا أصومه ولا آمرك ولا أنهاك إن شئت فصمه وإن شئت فلا تصمه
Its isnad is sahih, even though it appears to be disconnected. This has already come at 5080 and 5117, narrated by Ismail, who is Ibn Ulaya, from Ibn Abu Najeeh, from his father, who said, "Ibn Umar was asked." In 5080, Sufyan bin Uyayna's narration of it goes through Ibn Abu Najeeh, from his father, from someone who asked Ibn Umar, and we judged the connected version to be preferable there.