Wa in kuntum fee raibim mimmaa nazzalnaa 'alaa 'abdinaa fatoo bi Sooratim mim mislihee wad'oo shuhadaaa'akum min doonil laahi in kuntum saadiqeen
And if you be in doubt whether the Book We have sent down to Our Servant is from Us or not, then produce, at least, one Surah like this. You may call all your associates to assist you and avail yourselves of the help of any one other than Allah. If you are genuine in your doubt, do this.
