A Jewish man said to Umar bin Al Kattab, (O leader of the believers, there is a verse in your 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 celebration. What is the ayah to which he is referring?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

This verse is the following:

Allah Says (interpretation of meaning): {…This day, I have perfected your religion for you, completed My Favour upon you, and have chosen for you Islâm as your religion. …}[5:3].