Musnad Ahmad 27:424

Yazid narrated to us, he said: Al-Mas'udi informed us, from Abu Ja'far Muhammad ibn Ali, who said: While Ubayd ibn Umayr was narrating stories and Abdullah ibn Umar was with him, Ubayd ibn Umayr said: The Messenger of Allah, may Allah bless him and grant him peace, said: "The likeness of the hypocrite is like a sheep between two herds; when it comes to these, it butts it, and when it comes to those, it butts it." Ibn Umar said: The Messenger of Allah, may Allah bless him and grant him peace, did not say it like that. Rather, the Messenger of Allah, may Allah bless him and grant him peace, said: "Like a sheep between two flocks." He said: The old man became agitated and angry. When Abdullah saw that, he said: Had I not heard it, I would not have refuted you regarding it.