that is because there came to them their apostles with clear arguments but they said shall mortals guide us? so they disbelieved and turned back and allah does not stand in need and allah is selfsufficient praised.
ذلك بأنه كانت تأتيهم رسلهم بالبينات فقالوا أبشر يهدوننا فكفروا وتولوا واستغنى الله والله غني حميد