Musnad Abu Ya'la al-Mawsili 140:50

Al-Hakam ibn Musa narrated to us, Shihab ibn Khirash narrated to us, from Yazid al-Raqashi, Anas ibn Malik narrated to us, he said: The Messenger of Allah (peace be upon him) said: "I fear for my Ummah after me five things: denying the divine decree (Qadar), and believing in the stars."