Musnad Ahmad 27:1748

Harun ibn Ma'ruf narrated to us, Abdullah ibn Wahb informed us, Abu Sakhr informed me, from Nafi' who said: While we were sitting with Abdullah ibn Umar, a man came and said: "So-and-so sends you greetings," referring to a man from the people of Syria. Abdullah said: "It has reached me that he has introduced an innovation. If that is the case, then do not convey my greetings to him. I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'There will be in my nation transformation (into animals) and pelting (with stones), and that is regarding the Zindiqs (heretics) and the Qadariyyah (those who deny divine decree).'"