Jami` at-Tirmidhi 3043

Narrated Tariq bin Shihab:"A man among the Jews said to 'Umar bin Al-Khattab: 'O Commander of the Believers! If we were the ones unto whom this Ayah was revealed, 'This day, I have perfected your religion for you, completed My favor upon you, and have chosen for you Islam as your religion (5:3).' - then we would have taken that day as a day of celebration.' So 'Umar bin Al-Khattab said to him: 'Indeed I do know which day this Ayah was revealed upon. It was revealed on the Day of 'Arafah, on Friday