*Al-Hadid: (29) “So that the People of the Book may know that they have no power over anything of the bounty of Allah…”*
It is said that this relates to the content of the imperative sentence which contains the meaning of a condition, as the implication is: "If you fear Allah and believe in His Messenger, He will give you such and such, so that the People of the Book may know..."
Another view is that it relates to the three preceding verbs due to competition (tanaazu'), or to an implied meaning such as "He did that and made them know..." and the like. The "la" (no) is extra, as it is in the Almighty’s saying: "What prevented you that you should not prostrate (an la tasjuda)?" Its usage as an extra particle in the presence of contextual evidence is frequent.
"An" is the lightened form of the heavy anna (that), and its omitted noun is the pronoun referring to the People of the Book—meaning, "that they..." It is also said that it is the "pronoun of the affair" (dhamir al-sha'n), and what follows is its predicate. The entire clause is in the accusative position as the object of "know" (ya'lama), meaning: So that the People of the Book—who say: "Whoever among us believes in your Book has two rewards, and whoever does not believe in your Book has one reward like yours"—may know that they do not possess anything of Allah’s bounty, whether it be the two rewards or others, and that they cannot attain it as long as they do not believe in Muhammad (peace be upon him). The gist of this is to notify them that their faith in their own prophets will not benefit them at all unless they believe in the Prophet (peace be upon him). Thus, their saying, "Whoever does not believe in your book has one reward," is false.
Ibn Abi Hatim narrated from Muqatil ibn Hayyan: When the verse "These will be given their reward twice for what they endured" was revealed, the believers of the People of the Book boasted over the companions of the Prophet (peace be upon him), saying: "We have two rewards and you have one." This was difficult for his companions (peace be upon him), so Allah Almighty revealed: "O you who have believed..." (to the end of the passage). He, glory be to Him, granted them two rewards like those given to the believers of the People of the Book, and added the Light for them. Then He said, "So that the People of the Book may know..." The gist of this, according to this interpretation, is so that they may know they are not the sole owners of His bounty, so that they may boast of it over the believers and monopolize it for themselves to the exclusion of others.
His saying: "...and that the bounty is in the hand of Allah" is a conjunction to "that they have no power," entering with it into the sphere of what is to be known. His saying: "...He gives it to whom He wills" is a second predicate for "that," or it is the predicate, and what precedes it is, as has been said, a necessary state or an initiation. His saying: "And Allah is possessor of the great bounty" is a supplementary conclusion confirming the content of what preceded it.
Some have taken the view that the address is to those who believed from the People of the Book—the Jews and the Christians—or to those of them who will believe later. The meaning is: O you who have believed in Moses and Jesus (peace be upon them), believe in Muhammad (peace be upon him)—that is, remain steadfast in your faith in him or establish faith in him (peace be upon him)—and He will give you two portions of His mercy: one portion for your faith in those you believed in previously, and one portion for your faith in Muhammad (peace be upon him) lastly. This is so that those who did not believe from the People of the Book may know that they shall not attain anything of what the believers among them attain, nor will they be able to attain it, as they have not fulfilled its condition, which is faith in His Messenger (peace be upon him).
This is supported by what is in Sahih al-Bukhari: "Whoever has a slave girl whom he teaches and disciplines well, then emancipates and marries her, has two rewards; and any man of the People of the Book who believes in his prophet and then believes in me has two rewards; and any slave who fulfills the right of Allah and the right of his masters has two rewards." There is no difficulty in this regarding the Christians, and therefore it is said that the address is to them, because their religious path was not abrogated before the manifestation of the Muhammadan path, and their knowledge of it existed; thus, they are rewarded for acting upon it until it becomes incumbent upon them to believe in the Prophet (peace be upon him), and when they believe, they are rewarded again, so they have two rewards. Indeed, one might find difficulty regarding others, as their religious paths were abrogated by the path of Jesus (peace be upon him), and there is no reward for acting upon an abrogated path. The answer is that it is not impossible for them to be rewarded for acting upon their previous path, even if it was abrogated, by the blessing of Islam. Some have answered that the rewarding is for the very faith of that person of the Book in his prophet, even if the law was abrogated, because faith in every prophet is an obligation, whether the law was abrogated or not.
It is said that the "la" in "so that the People of the Book may not know" (li-alla ya'lama) is not extra, and the pronoun in "they have no power" (la yaqdiruna) refers to the Prophet (peace be upon him) and the believers. That is: We did what We did so that the People of the Book would not believe that the Prophet (peace be upon him) and those who believe in him have no power over anything of the bounty of Allah, which refers to the happiness of the two abodes that they have been granted, and that they cannot attain it. Or that they—the Prophet and the believers—have no power, etc., such that their lack of knowledge regarding their lack of power is a metonym for their knowledge of their actual power. Thus, His saying: "...and that the bounty is in the hand of Allah" is conjoined to "that they may know," entering with it into the sphere of the causation (ta'lil) rather than "that they have no power." It is as if it were said: We did what We did so that they would not believe such-and-such, and because the bounty is in the hand of Allah. Thus, it is a case of conjoining an objective to an objective, based on the well-known rule. Due to the strain involved in this interpretation and its contradiction of some readings, most exegetes have not adopted it.