Musnad Ahmad 32:431

Bahz narrated to us, Shu'bah narrated to us, 'Ubayd Allah ibn Abi Bakr informed me, from Anas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) was asked about the major sins, or he mentioned them, and he said: "Associating partners with Allah (shirk), disobedience to parents, killing a soul, and false testimony, or false speech."