Musnad Ahmad 27:630

He said: I found in my father’s book: Ishaq ibn Yusuf narrated to us, Ubaydullah narrated to us, from Nafi’, from Ibn Umar, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The likeness of the hypocrite is like the ewe wandering between two flocks; she goes to this one at one time, and to this one at another time, not knowing which of them she should follow."