And those who disbelieve say: wherefore is not a sign sent down unto him from his Lord! Say thou: verily Allah sendeth astray whomsoever He will and guideth unto Himself whosoever turnoth in penitence. 27 Who have believed and whose hearts have rest in the remembrance of Allah. Verily in the remembrance of Allah do hearts find rest! 28 "As for those who believe and do righteous deeds -- blissful is their end." 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 Had there been a Qur'an which could have made the mountains move, or the earth to cleave asunder, or the dead to speak, yet all authority belongs to God. Have the believers not learnt that if God had so willed He could have guided all mankind? As for unbelievers, they will be visited by misfortune endlessly for what they have done; or it would sit in their homes till the promised threat of God comes to pass. Surely God does not go back on His promise. 31