Musnad Ahmad 32:399

'Abd al-Rahman ibn Mahdi narrated to us, from Sufyan, from Yahya ibn Hani', from 'Abd al-Hamid ibn Mahmud, who said: I prayed with Anas on a Friday, and we were pushed toward the pillars, so we moved forward or backward. Anas said: "We used to avoid this during the time of the Messenger of Allah, may Allah bless him and grant him peace."