(a) Tariq bin Shihab said: A man from the Jews came to Sayyiduna Umar (may Allah be pleased with him) and said: O Commander of the Believers! There is a verse in your Book which you recite; had it been revealed upon us, the community of Jews, we would have taken that day as a festival (Eid). He asked: Which verse? He said: "This day I have perfected for you your religion, completed My favour upon you, and approved for you Islam as your religion." [Surah al-Ma'idah: 3] Sayyiduna Umar (may Allah be pleased with him) said: I know well the day and the place in which this verse was revealed. It was revealed to the Messenger of Allah (peace and blessings be upon him) at Arafat, on a Friday.
(b) Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) said that on that day the Prophet (peace and blessings be upon him) prayed the Zuhr prayer, not the Friday prayer.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجمعة / 5622