Musnad Ahmad 110:5

Al-Hajjaj narrated to us, Al-Layth—meaning Ibn Sa’d—narrated to us, he said: Yazid ibn Abi Habib narrated to me, that Ja’far ibn Abdullah ibn al-Hakam narrated to him, from Tamim ibn Mahmud al-Laythi, from Abd al-Rahman ibn Shibl al-Ansari, that he said: "The Messenger of Allah (peace and blessings of Allah be upon him) forbade three things in prayer: the pecking of the crow, the spreading of the beast of prey, and that a man should designate a single place [in the mosque] for himself just as a camel designates its place."