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 have believed and whose hearts are assured by the remembrance of Allah. Unquestionably, by the remembrance of Allah hearts are assured." 28 of those who believe and do righteous deeds; theirs is blessedness and a fair resort. 29 Thus We have sent you to a people, before whom other peoples have passed away, so that you may recite to them what We have revealed to you. Yet they deny the Gracious God. Say, "He is my Lord; there is no god but He. In Him I put my trust and to Him I shall return." 30 If only a Koran whereby the mountains were set in motion, or the earth were cleft, or the dead were spoken to -- nay, but God's is the affair altogether. Did not the believers know that, if God had willed, He would have guided men all together? And still the unbelievers are smitten by a shattering for what they wrought, or it alights nigh their habitation, until God's promise comes; and God will not fail the tryst. 31