The unbelievers say, 'Why has a sign not been sent down upon him from his Lord?' Say: 'God leads astray whomsoever He will, and He guides to Him all who are penitent.' 27 Those who believe, their hearts being at rest in God's remembrance -- in God's remembrance are at rest the hearts 28 (As for) those who believe and do good, a good final state shall be theirs and a goodly return. 29 Thus We have sent thee among a nation before which other nations have passed away, to recite to them that We have revealed to thee; and yet they disbelieve in the All-merciful. Say: 'He is my Lord -- there is no god but He. In Him I have put my trust, and to Him I turn.' 30 Had it been possible for a Lecture to cause the mountains to move, or the earth to be torn asunder, or the dead to speak, (this Qur'an would have done so). Nay, but Allah's is the whole command. Do not those who believe know that, had Allah willed, He could have guided all mankind? As for those who disbelieve, disaster ceaseth not to strike them because of what they do, or it dwelleth near their home until the threat of Allah come to pass. Lo! Allah faileth not to keep the tryst. 31