Al-Baqara 2:123

We mentioned a similar Ayah at the beginning of this Surah, and it is mentioned here to emphisize the importance of following the Ummi Prophet and Messenger, who is described for the People of the Scriptures in their Books by his characteristics, name, the good news about him and the description of his Ummah. Allah warned them against concealing this information, which is among the favors that Allah granted them. Allah also commanded them to remember their daily life and their religious affairs and how He blessed them. They should not envy their cousins, the Arabs, for what Allah has given them, the Final Messenger of Allah ﷺ being an Arab. Envy should not incite them to oppose or deny the Prophet or refrain from following him, may Allah's peace and blessings be upon him until the Day of Judgment.

A large section of this Sarah, ending with the previous verse, has been dealing with different aspects of the conduct of the Israelites (that is, the Jews) in the course of their history. This account had begun with the statement which has been repeated at the end in these two verses. The statement is of a general and principal kind, and the verses which come in between the beginning and the end are, so to say, a detailed demonstration of the statement. On the one hand, it encourages the Israelites to come back to the Straight Path by reminding them of the blessings which Allah has bestowed on them; on the other hand, it warns them of the consequences of their lapses by depicting the Day of Judgment. The purpose of repeating the statement at the end of the discussion is to make the two ideas sink deep into their minds. For, what is aimed at in a discussion is the affirmation of certain basic and general principles -- being succinct, they are easily kept alive in the mind, and, being comprehensive and readily applicable to particular situations, they make it easy for one to remember the details too. In the art of writing and speaking, it is considered to be one of the most effective means of carrying conviction that, before starting on a long analytical discussion of a subject, one should define the basic ideas very briefly and clearly which are always helpful in comprehending the details and the particularities, and that, in concluding the argument, one should repeat these ideas by way of a summary. The repetition of the introductory statement here is of this very nature.