It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: The ruler is a shield; fighting is done behind him and through him, piety is adopted. If he gives a ruling based on piety and justice, he will be rewarded for it, and if he gives any wrong ruling besides that, its burden will be upon him.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 10777