Those who deny the truth ask, "Why has no Sign been sent down to him by his Lord?" Say, "God lets go astray those whom He wills and guides to Himself those who turn to Him, 27 those who believe and whose hearts find comfort in the remembrance of God -- surely in the remembrance of God hearts can find comfort. 28 The righteously striving believers will receive abundant blessings and the best eternal dwelling. 29 That is how We have sent you to a people before whom many a people have come and gone, so that you may announce to them whatever We have revealed to you. But they do not believe in Ar-Rahman. Tell them: "He is my Lord. There is no other god but He. In Him have I placed my trust, and to Him is my reversion." 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