And those who disbelieved say, "Why has a sign not been sent down to him from his Lord?" Say, [O Muhammad], "Indeed, Allah leaves astray whom He wills and guides to Himself whoever turns back [to Him] - 27 Those who believe and find peace in their hearts from the contemplation of God: Surely there is peace of heart in the contemplation of God!" 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 And even if there were a Quran with which the mountains were made to pass away, or the earth were travelled over with it, or the dead were made to speak thereby; nay! the commandment is wholly Allah's, Have not yet those who believe known that if Allah please He would certainly guide all the people? And (as for) those who disbelieve, there will not cease to afflict them because of what they do a repelling calamity, or it will alight close by their abodes, until the promise of Allah comes about; surely Allah will not fail in (His) promise. 31