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 They are those who believe and whose hearts find rest in the remembrance of Allah. Lo! in the remembrance of Allah hearts do find rest. 28 of those who believe and do righteous deeds; theirs is blessedness and a fair resort. 29 Thus have We raised thee [O Muhammad] as Our Apostle amidst a community [of unbelievers] before whose time [similar] communities have come and gone, so that thou might propound to them what We have revealed unto thee: for [in their ignorance] they deny the Most Gracious! Say: "He is my Sustainer. There is no deity save Him. In Him have I placed my trust, and unto Him is my recourse!" 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