Those who disbelieve say: If only a portent were sent down upon him from his Lord! Say: Lo! Allah sendeth whom He will astray, and guideth unto Himself all who turn (unto Him), 27 Those who believe, their hearts being at rest in God's remembrance -- in God's remembrance are at rest the hearts 28 of those who believe and do righteous deeds; theirs is blessedness and a fair resort. 29 Thus We have sent thee unto a community before whom other communities have passed away, in order that thou mayest recite unto them that which We have revealed unto thee; yet they disbelieve in the Compassionate. Say thou: He is my Lord, there is no god but he; on Him I rely, and unto Him is my return in penitence. 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