And those who disbelieved say, "Why has a sign not been sent down to him from his Lord?" Say, [O Muhammad], "Indeed, Allah leaves astray whom He wills and guides to Himself whoever turns back [to Him] - 27 and the faithful ones whose hearts are comforted by the remembrance of God. Remembrance of God certainly brings comfort to all hearts. 28 [and so it is that] they who attain to faith and do righteous deeds are destined for happiness [in this world] and the most beauteous of all goals [in the life to come]!" 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 And even if there were a Quran with which the mountains were made to pass away, or the earth were travelled over with it, or the dead were made to speak thereby; nay! the commandment is wholly Allah's, Have not yet those who believe known that if Allah please He would certainly guide all the people? And (as for) those who disbelieve, there will not cease to afflict them because of what they do a repelling calamity, or it will alight close by their abodes, until the promise of Allah comes about; surely Allah will not fail in (His) promise. 31