Sahih Muslim Book 043, Hadith Number 7153.
Chapter : Not known.
Tariq b. Shihab reported that a Jew said to 'Umar: You recite a verse which, if it had been revealed in relation to us, we would have taken that day as the day of rejoicing. Thereupon 'Umar said: I know where it was revealed and on the day when it was revealed and where Allah's Messenger (may peace be upon him) had been at that time when it was revealed. It was revealed on the day of 'Arafa (ninth of Dhu'l Hijjah) and Allah's Messenger (may peace be upon him) had been staying in 'Arafat. Sufyan said: I doubt, whether it was Friday or not (and the verse referred to) is this: "Today I have perfected your religion for you and completed My favours upon you "(v. 4).