Musnad Ahmad 27:1933

'Abd al-Razzaq narrated to us, Sufyan al-Thawri informed us, from 'Abd al-Karim al-Jazari, from Sa'id ibn Jubayr, who said: I saw Ibn 'Umar walking between al-Safa and al-Marwah. Then he said: "If I walk, I have seen the Messenger of Allah, may Allah bless him and grant him peace, walking; and if I run, I have seen the Messenger of Allah, may Allah bless him and grant him peace, running."