۞ And remember the brother of Ad, when he warned his people beside the sand-dunes -- and already warners had passed away alike before him and behind him -- saying, 'Serve none but God! Truly I fear for you the chastisement of a dreadful day. 21 They said: art thou come unto us that thou mayest turn us aside from our gods? then bring thou upon us that wherewith thou threatenest us, if thou art of the truth-tellers. 22 He said: "The knowledge (of the time of its coming) is with Allah only, and I convey to you that wherewith I have been sent, but I see that you are a people given to ignorance!" 23 Then, when they saw the (Penalty in the shape of) a cloud traversing the sky, coming to meet their valleys, they said, "This cloud will give us rain!" "Nay, it is the (Calamity) ye were asking to be hastened!- A wind wherein is a Grievous Penalty! 24 which will destroy everything at its Lord's behest!" And in the morning there was nothing left to be seen save their [empty] dwellings: thus We repay the evil-doers. 25 And assuredly We had established them in that flourishing condition wherein We have not established you, and We had appointed for them hearing and sight and hearts; yet their hearing and sight and heart availed them not at all, they became wont to gainsay the revelations of Allah, and surrounded them that whereat they had been mocking. 26