Musnad Ahmad 27:524

Muhammad ibn Bishr narrated to us, from Ubaydullah, from Umar ibn Nafi, from Nafi, from Abdullah ibn Umar, who said: "The Messenger of Allah, may Allah bless him and grant him peace, forbade *al-qaza*." Ubaydullah said: "And *al-qaza* is patching the head [shaving parts of the head and leaving others]."