Ar-Ra'd: 7

"And those who disbelieve say..." (They are those who are hasty, as narrated from Qatadah. It is as if they were described as such to denounce their disbelief in the signs of Allah—signs before which the solid mountains would crumble—since they paid no heed to them and did not even consider them to be of the nature of signs. They said, "Why has a sign not been sent down upon him from his Lord?"—such as the signs of Moses and Jesus, peace be upon them, like turning a staff into a serpent or bringing the dead to life, out of obstinacy or arrogance. Otherwise, even in the slightest sign revealed to him, blessings and peace be upon him, there is sufficiency and a lesson for those of understanding. Using the present tense is to bring the past state to mind; it is also possible that it is an indication that this statement is their habitual practice. The tanwin on "sign" (ayah) denotes aggrandizement, though it is also permissible that it denotes unity.)

"You are only a warner..." (sent to warn of the evil consequences of what Allah has forbidden, just like the messengers before you. It is not upon you but to bring forth that by which your prophethood is known, and this has been achieved to a degree beyond which there is no further need, nor is there any necessity to silence them by producing what they proposed.)

"And for every people is a guide."

(Meaning: a prophet who calls to the Truth and guides towards it with a sign appropriate to him and his era. The indefiniteness [of 'a guide'] is for the purpose of ambiguity. This is also narrated from Qatadah and Mujahid; upon this interpretation, the saying of the Exalted...)