Sahih Bukhari | Volume 9 | Hadith Number 373
Narrated by Tariq bin Shihab
A Jew said to 'Umar, "O Chief of the Believers, if this verse: 'This day I have perfected your religion for you, completed My favors upon you, and have chosen for you, Islam as your religion.' (5:3) had been revealed upon us, we would have taken that day as an 'Id (festival) day." 'Umar said, "I know definitely on what day this Verse was revealed; it was revealed on the day of 'Arafat, on a Friday."