Sahih Al Bukhari (45)

حَدَّثنا الحَسَنُ بْنُ الصَّبَّاحِ، سَمِعَ جَعْفَرَ بْنَ عَوْنٍ، حَدَّثنا أَبُو العُمَيْسِ، أَخبَرَنا قَيْسُ بْنُ مُسْلِمٍ، عَنْ طَارِقِ بْنِ شِهَابٍ، عَنْ عُمَرَ بْنِ الخَطَّابِ، أَنَّ رَجُلاً مِنَ اليَهُودِ قَالَ لَهُ: يَا أَمِيرَ المُؤْمِنِينَ، آيَةٌ فِي كِتَابِكُمْ تَقْرَؤُونَهَا، لَوْ عَلَيْنَا مَعْشَرَ اليَهُودِ نَزَلَتْ، لاَتَّخَذْنَا ذَلِكَ اليَوْمَ عِيدًا، قَالَ: أَيُّ آيَةٍ؟ قَالَ: {اليَوْمَ أَكْمَلْتُ لَكُمْ دِينَكُمْ وَأَتْمَمْتُ عَلَيْكُمْ نِعْمَتِي وَرَضِيتُ لَكُمُ الإِسْلاَمَ دِينًا} قَالَ عُمَرُ: قَدْ عَرَفْنَا ذَلِكَ اليَوْمَ، وَالمَكَانَ الَّذِي نَزَلَتْ فِيهِ عَلَى النَّبِيِّ صَلى الله عَلَيهِ وسَلمَ، وَهُوَ قَائِمٌ بِعَرَفَةَ يَوْمَ جُمُعَةٍ.

`Umar ibn Al Khattab (may Allah be pleased with him) narrated: Once a Jew said to me: "O the chief of believers! There is an Ayah in your Sacred Book which is read by all of you (Muslims), and had it been revealed to us, we would have taken that day (on which it was revealed) as a day of celebration." `Umar ibn Al Khattab asked: "Which is that Ayah?" The Jew replied: "This day I have perfected your religion for you, completed My favor upon you, And have chosen for you Islam as your religion." `Umar replied: "No doubt, we know when and where this Ayah was revealed to the Prophet (peace be upon him). It was Friday and the Prophet (peace be upon him) was standing at `Arafat (i.e. the Day of Hajj)."