Musnad Abu Ya'la al-Mawsili 155:61

Al-Harith ibn Surayj narrated to us, Ibn al-Mubarak narrated to us, from al-Awza'i, from al-Zuhri, from Abu Salamah, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "There is no ruler—or he said: prophet—except that he has two inner circles (bitanatan): an inner circle that commands him to do good and forbids him from evil, and an inner circle that does not spare him any corruption. So whoever is protected from their evil has indeed been protected."