The unbelievers say, 'Why has a sign not been sent down upon him from his Lord?' Say: 'God leads astray whomsoever He will, and He guides to Him all who are penitent.' 27 Those who believe, their hearts being at rest in God's remembrance -- in God's remembrance are at rest the hearts 28 Those who believe (in the Oneness of Allah - Islamic Monotheism), and work righteousness, Tuba (it means all kinds of happiness or name of a tree in Paradise) is for them and a beautiful place of (final) return. 29 Thus We have sent thee among a nation before which other nations have passed away, to recite to them that We have revealed to thee; and yet they disbelieve in the All-merciful. Say: 'He is my Lord -- there is no god but He. In Him I have put my trust, and to Him I turn.' 30 Even if there were a Quran by which mountains could be set in motion, by which the earth could be rent asunder, or by which the dead could be made to speak [they would not believe in it]. Surely all things are subject to God's will. Are the faithful unaware that, had He pleased, God could have guided all mankind? Calamity shall not cease to strike those who deny the truth because of their misdeeds or to strike near their homes, until God's promise be fulfilled. God will not fail to keep His promise. 31