Abu Sa`id and Abu Hurairah (May Allah be pleased with him) reported: Messenger of Allah (PBUH) said, "Allah neither raised up any Prophet nor did He authorize any person with ruling power but for whom there were two types of entourage: one enjoins upon him to do good and incites him to carry it out, and the other enjoins evil and goads him; and the protected (from the bad entourage) is the one whom Allah protects."[Al-Bukhari].
Aruler has been told here that Taqwa (consciousness and fear of Allah), honesty, integrity and ability are the prerequisites to chosing anybody as his aide or advisor. Prior to their nomination, he should check up the reputation of his advisors. This precautionary measure will serve as a safeguard against the spread of corruption in society and serve the cause of goodness. Secondly, a ruler should obey the Commands of Allah and His Messenger (PBUH) because this discipline will not only keep him safe from making faults but will also serve as a shield against the machinations of wicked people.