Tariq bin Shihab says: A Jew said to Sayyiduna Umar (may Allah be pleased with him): If we Jews knew when this verse was revealed, we would declare that day as a day of Eid. "This day I have perfected your religion for you." And if even now we come to know the day on which this verse was revealed, we would declare that day as a day of Eid. So Sayyiduna Umar (may Allah be pleased with him) said: I know about the day on which this verse was revealed, and I also know about the night in which it was revealed: it was the day of Friday, and at that time we were with the Prophet (peace and blessings be upon him) at Arafat.
Hadith Referenceصحیح ابن حبان / كتاب الإيمان / 185
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - «صحيح سنن النسائي» (2808): ق.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط الشيخين.