Musnad Abu Ya'la al-Mawsili 136:1

Abu Khaythama narrated to us, Jarir narrated to us, from al-A'mash, from Bukayr al-Jazari, from Sahl Abu al-Aswad, from Anas ibn Malik, who said: We were in a house, and the Messenger of Allah (may Allah bless him and grant him peace) stood at the door of the house and said: "The leaders are from Quraysh. They have a right over you, and you have the like of it over them, provided they do three things: if they are asked for mercy, they show mercy; if they judge, they act justly; and if they make a covenant, they fulfill it. Whoever among them does not do that, then upon him is the curse of Allah, the angels, and all of mankind."