Musnad Ahmad 31:550

'Abd al-Razzaq narrated to us, Dawud ibn Qays narrated to us, from Zayd ibn Aslam, from 'Abd al-Rahman ibn Abi Sa'id, from Abu Sa'id al-Khudri, who said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "If someone intends to pass between you and your sutrah (barrier), then turn him back. If he refuses, then push him away. If he refuses, then fight him, for he is only a devil."