Musnad Ahmad 1101:8

Yazid ibn Abd Rabbih narrated to us, Baqiyyah ibn al-Walid narrated to us, Isma'il ibn 'Ayyash narrated to me, from Damdam ibn Zur'ah, from Shurayh ibn 'Ubayd, from Jubayr ibn Nufayr and 'Amr ibn al-Aswad, from al-Miqdad ibn al-Aswad and Abu Umamah, they said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Indeed, the leader, when he seeks out suspicion among the people, corrupts them."