Jami` at-Tirmidhi 751
جامع الترمذي#751Da'ifIbn Abi Najib narrated from his father who said:"Ibn Umar was asked about fasting (the Day of) Arafah (at Arafat). He said: 'I performed Hajj with the Prophet, 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 no fast it, nor order it nor forbid it
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Ahmad Muhammad ShakirSahih Isnaad
Al-AlbaniSahih Isnaad
Zubair Ali ZaiDaif
In-book reference: 8:70