Musnad Ahmad 938:39

Ya'qub narrated to us, my father narrated to us, from Ibn Ishaq, Nafi' narrated to me, from Ibn 'Umar, from Zayd ibn Thabit, who said: "The Messenger of Allah, peace and blessings of Allah be upon him, forbade *al-muhaqalah* and *al-muzabanah*."