Those who have rejected (the message of Muhammad) say: "Why has no sign been sent down upon him from his Lord?" Tell them: "Allah lets go astray those whom He wills, and guides to Himself those who turn to Him." 27 Those who believe (in the Oneness of Allah - Islamic Monotheism), and whose hearts find rest in the remembrance of Allah, Verily, in the remembrance of Allah do hearts find rest. 28 The righteously striving believers will receive abundant blessings and the best eternal dwelling. 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