The Book on Government (Kitab Al-Imara)
Muslim :: Book 20 : Hadith 4519
It has been narrated on the authority of Abu Huraira that the Messenger of Allah (may peace be upon him) said: Whoso obeys me obeys God; and whose disobeys me disobeys God. Whoso obeys my commander obeys me, and whoso disobeys my commander disobeys me.