If this verse were revealed in relation to the Jews (i e. "This day I have perfected your religion for you and have completed My favours for you and have chosen for you al-Islam as religion") we would have taken the day of rejoicing on which this verse was revealed. Thereupon 'Umar said: I know the day on which it was revealed and the hour when it was revealed and where Messenger of Allah ﷺ had been when it was revealed. It was revealed on the night of Friday and we were in 'Arafat with Messenger of Allah ﷺ at that time.
قَالَتِ الْيَهُودُ لِعُمَرَ لَوْ عَلَيْنَا مَعْشَرَ يَهُودَ نَزَلَتْ هَذِهِ الآيَةُ { الْيَوْمَ أَكْمَلْتُ لَكُمْ دِينَكُمْ وَأَتْمَمْتُ عَلَيْكُمْ نِعْمَتِي وَرَضِيتُ لَكُمُ الإِسْلاَمَ دِينًا} نَعْلَمُ الْيَوْمَ الَّذِي أُنْزِلَتْ فِيهِ لاَتَّخَذْنَا ذَلِكَ الْيَوْمَ عِيدًا قَالَ فَقَالَ عُمَرُ فَقَدْ عَلِمْتُ الْيَوْمَ الَّذِي أُنْزِلَتْ فِيهِ وَالسَّاعَةَ وَأَيْنَ رَسُولُ اللَّهِ ﷺ حِينَ نَزَلَتْ نَزَلَتْ لَيْلَةَ جَمْعٍ وَنَحْنُ مَعَ رَسُولِ اللَّهِ ﷺ بِعَرَفَاتٍ