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 Messenger of Allah ﷺ had been at that time when it was revealed. It was revealed on the day of 'Arafa (ninth of Dhu'l Hijjah) and Messenger of Allah ﷺ 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).
أَنَّ الْيَهُودَ قَالُوا لِعُمَرَ إِنَّكُمْ تَقْرَءُونَ آيَةً لَوْ أُنْزِلَتْ فِينَا لاَتَّخَذْنَا ذَلِكَ الْيَوْمَ عِيدًا فَقَالَ عُمَرُ إِنِّي لأَعْلَمُ حَيْثُ أُنْزِلَتْ وَأَىَّ يَوْمٍ أُنْزِلَتْ وَأَيْنَ رَسُولُ اللَّهِ ﷺ حَيْثُ أُنْزِلَتْ أُنْزِلَتْ بِعَرَفَةَ وَرَسُولُ اللَّهِ ﷺ وَاقِفٌ بِعَرَفَةَ قَالَ سُفْيَانُ أَشُكُّ كَانَ يَوْمَ جُمُعَةٍ أَمْ لاَ يَعْنِي { الْيَوْمَ أَكْمَلْتُ لَكُمْ دِينَكُمْ وَأَتْمَمْتُ عَلَيْكُمْ نِعْمَتِي}