Tafsir of Fussilat 41:45

(And We certainly gave Musa the Book, so it was differed over therein). This is a fresh statement, presented to demonstrate that disagreement regarding the books is an ancient habit of nations, not specific to your people, in accordance with the method of the Exalted saying: "Nothing is said to you except what was already said to the messengers before you," as you have heard previously. That is, by Allah, We gave Musa the Torah, and it was differed over therein—some believing in it and some disbelieving. Such is the state of your people regarding what We have given you of the Qur’an; some believe in it and some disbelieve.

(And if not for a word that preceded from your Lord) regarding your disbelieving nation—namely, the promise to delay their punishment and to postpone the adjudication of the dispute between them and the believers until the Day of Resurrection, in the manner of the Exalted saying: "Rather, the Hour is their appointment," and His saying, the Glorified: "But He delays them until a specified term"—(it would have been judged between them) by the extirpation of the disbelievers, just as was done with the disbelievers of the previous nations.

(And indeed they) i.e., the disbelievers of your people (are in doubt concerning it) i.e., concerning the Qur’an (suspicious), meaning that which causes anxiety and disturbance. It is said: the second pronoun refers to the Torah, and the first to the Jews, based on the context, because they are the ones who differed regarding the book of Musa, peace be upon him; but this is not correct.