From Sahih Muslim (Hadith 4772):
It has been narrated on the authority of Abu Huraira that the Prophet of Allah (ﷺ) said:A commander (of the Muslims) is a shield for them. They fight behind him and they are protected by (him from tyrants and aggressors). If he enjoins fear of God, the Exalted and Glorious, and dispenses justice, there will be a (great) reward for him; and if he enjoins otherwise, it redounds on him
Reference: Muslim 4772