Those who have rejected (the message of Muhammad) say: "Why has no sign been sent down upon him from his Lord?" Tell them: "Allah lets go astray those whom He wills, and guides to Himself those who turn 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 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 If there were a Qur'an with which mountains were moved, or the earth were cloven asunder, or the dead were made to speak, (this would be the one!) But, truly, the command is with Allah in all things! Do not the Believers know, that, had Allah (so) willed, He could have guided all mankind (to the right)? But the Unbelievers,- never will disaster cease to seize them for their (ill) deeds, or to settle close to their homes, until the promise of Allah come to pass, for, verily, Allah will not fail in His promise. 31