In The Name of Allah, The Most Merciful, The Bestower of Mercyu.

Abu Hurairah, may Allah be pleased with him, said, “The Prophet, peace and blessings of Allah be upon him, said, “Verily, the leader is a shield behind whom they fight and he protects them. If he commands (people to) fear Allah, The Exalted, and justice, then he will have a reward. If he commands something else, then it will be against him’”. [S‌ah‌ih Muslim 1841]

“The leader is a shield”.  Imam An-Nawawi, may Allah have mercy upon him, said, he is like a shelter because he prevents the enemy from harming the Muslims, preventing the people from (harming) one another, protecting the Muslim nation and the people fearing his authority. “Behind whom they fight”, meaning, alongside him they fight against the unbelievers (i.e. those at war with his country), the rebels, the kharijites and all the perpetrators of corruption and oppression. [Sharh Sahih Muslim 12/193. Publisher, Daar Al-Kutub al-Ilmiyyah. 1st Edition 1421AH (2000)]