Musnad Ahmad 27:1415

Qutaybah narrated to us, Rashdin narrated to us, from Abu Sakhr Humayd ibn Ziyad, from Nafi’, from Ibn Umar, who said: I heard the Messenger of Allah, may Allah bless him and grant him peace, say: "There will be in this nation transformation (into animals). Behold, that is among those who deny the Divine Decree (Qadar) and the Zindiqs (heretics)."