A word on the verse (Today I have perfected for you your religion and completed My favor upon you and chosen for you Islam as your religion).

The Shaykh : The man was one of the great rabbis and scholars of the Jews whom Allah Mighty and Majestic guided to Islam, so they embraced Islam. He was Ka'b al-Ahbar. One day he came to 'Umar ibn al-Khattab (may Allah be pleased with him) and said, "O Commander of the Faithful, there is a verse in the Book of Allah that, had it been revealed to us, the Jews, we would have taken the day of its revelation as a festival." He said, "What is it?" He mentioned this verse 'Umar said, "I am the most knowledgeable of people about that. It was revealed on two festival days: the Prophet was at 'Arafah, and it was Friday." This verse was revealed while the Prophet was at 'Arafah, meaning during the Farewell Pilgrimage, and the Day of 'Arafah at that time was a Friday. So it is as if he is saying to that Jew who had embraced Islam, "Rejoice in all good, for the day you wished for, Allah Mighty and Majestic has made it so by revealing this verse to the Messenger of Allah (peace and blessings be upon him) on a Friday while he was at 'Arafah." The meaning of this statement is that Allah bestows a favor upon His Muslim servants by making the religion complete, such that no one needs to add to it, not even a single act of worship. Therefore, he (peace and blessings be upon him) said, as an explanation and clarification and interpretation of this verse, He also said (peace and blessings be upon him), clarifying that this clarification is not a matter specific to our Prophet, the Seal of the Prophets, but rather it was obligatory for every prophet, because Allah Mighty and Majestic sent him as a guidance for all people in every time. As for our Messenger, He sent him as a guidance for all people, with no prophet after him. So he (peace and blessings be upon him) said, as in Sahih Muslim, (peace and blessings be upon him), whether he was an earlier or a later prophet, And our Messenger (peace and blessings be upon him) is among these prophets who came with a complete message, with no message after it and no prophet after him (peace and blessings be upon him). Therefore, it is no longer permissible for Muslims to exercise independent legal reasoning in acts of worship. As for independent legal reasoning in transactions, which are repeated, new, varied, and differ from region to region and from country to country, that is where independent legal reasoning applies. But as for independent legal reasoning in acts of worship, the matter is complete, so there is no independent legal reasoning, as the jurists say in the case of an explicit text. If you know this reality, you will know that the call to the truth, among the many calls whose shouts you hear today, many and very many, is the call that commands all Muslims to return in their religion to the Book of Allah and the Hadith of the Messenger of Allah (peace and blessings be upon him and his family), and to the methodology of the righteous predecessors who were guided by his guidance (peace and blessings be upon him) and did not add to it, not even a little, not a large thing or a small thing...