۞ And make mention (O Muhammad) of the brother of A'ad when he warned his folk among the wind-curved sandhills - and verily warners came and went before and after him - saying: Serve none but Allah. Lo! I fear for you the doom of a tremendous Day. 21 They said: "Hast thou come in order to turn us aside from our gods? Then bring upon us the (calamity) with which thou dost threaten us, if thou art telling the truth?" 22 He said: "The Knowledge (of when it will come) is only with Allah: I proclaim to you the mission on which I have been sent: But I see that ye are a people in ignorance!".. 23 Then when they beheld it as an overpeering cloud tending toward their valleys they said: yonder is an overpeering cloud bringing us rain. Nay it is that which ye sought to be hastened: a wind wherein is a torment afflictive. 24 Destroying everything by the command of its Lord, so they became such that naught could be seen except their dwellings. Thus do We reward the guilty people. 25 And yet, We had established them securely in a manner in which We have never established you, [O people of later times;] and We had endowed them with hearing, and sight, and [knowledgeable] hearts: but neither their hearing, nor their sight, nor their hearts were of the least avail to them, seeing that they went on rejecting God's messages; and [in the end] they were overwhelmed by the very thing which they had been wont to deride. 26