Allah the Exalted says:

“And those before them also denied, though these have not attained even a tenth of what We gave them. Yet they denied My messengers, so how severe was My condemnation! (45) Say, ‘I urge you to one thing only: that you stand for Allah, in pairs and singly, then reflect. There is no madness in your companion; he is only a warner to you before a severe punishment.’ (46) Say, ‘Whatever reward I may have asked of you, it is yours. My reward is only with Allah, and He is Witness over all things.’ (47) Say, ‘Indeed, my Lord sends down the truth; He is the Knower of all that is unseen.’ (48)”

“And those before them also denied”: the earlier nations denied Our messengers. They were ‘Ad, Thamud, the people of Abraham, the people of Lot, and others besides them. “Though these have not attained”—that is, these polytheists—“even a tenth,” meaning one tenth, “of what We gave them,” that is, of the strength, blessings, and long lives We granted the former nations. “Yet they denied My messengers, so how severe was My condemnation!” That is, My condemnation and retribution against them. By this, He warns the disbelievers of this community against the punishment that befell the earlier nations.

“Say, ‘I urge you to one thing only’”: I command and counsel you to one matter, that is, to a single quality. He then explains that quality: “that you stand for Allah,” meaning for the sake of Allah, “in pairs,” that is, two by two, “and singly,” that is, one by one, “then reflect.” That is, gather together, examine the matter, discuss it, and then each reflect individually upon the condition of Muhammad, peace and blessings be upon him, and thus come to know that “there is no madness in your companion.” The standing meant here is not standing as opposed to sitting; rather, it means earnest engagement in seeking the truth, as in His words: “and that you deal justly with orphans” (4:127).

“He is only a warner to you before a severe punishment.” Muqatil said: The statement ends at the words, “then reflect”—that is, upon the creation of the heavens and the earth, so that you may know that their Creator is One, having no partner. Then a new statement begins: “There is no madness in your companion.”

“Say, ‘Whatever reward I may have asked of you’” for conveying the message—“whatever reward,” meaning payment—“it is yours.” In other words, say: I ask no payment from you for conveying the message, lest you accuse me. The meaning of “it is yours” is that I have asked nothing of you, just as someone might say, “I have no claim to this; I have given it to you,” meaning that he has no share in it. “My reward,” that is, my recompense, “is only with Allah, and He is Witness over all things.”

“Say, ‘Indeed, my Lord sends down the truth.’” Casting may refer to shooting with an arrow, throwing pebbles, or speaking. Its meaning here is that He brings the truth and revelation, sending it down from heaven and conveying it to the prophets. “He is the Knower of all that is unseen”: this is in the nominative as the predicate of “indeed”; that is, He is the Knower of all that is unseen.