Musnad Abu Ya'la al-Mawsili 152:62

Zuhayr ibn Harb narrated to us, Jarir narrated to us, from Mansur, from Abu Wa'il, from 'Amr ibn Sharhabil, from 'Abdullah, who said: I asked the Messenger of Allah (peace and blessings of Allah be upon him), "Which sin is the greatest in the sight of Allah?" He said, "That you set up a rival to Allah, while He created you." I said, "Indeed, that is great." I said, "Then what?" He said, "That you kill your child out of fear that he will eat with you." I said, "Then what?" He said, "That you commit adultery with the wife of your neighbor."